Verify that it's actually distortion you're hearing rather than, say, crackling from short dropouts due to buffer underflows. Do you hear the distortion on individual soloed tracks, or only in the full mix? Can you see obvious clipping if you freeze a track with fx?

Not sure I'm understanding fully but the DAW can't introduce distortion into the recorded signal itself.
We're writing what comes in through your A2D's via the audio interface. No processing is done other than DC offset if selected.
If you open the projects in older versions of SONAR and play them do you hear the same distortion? If not its surely not present in the audio data itself.

Hi guys. sorry, been away working my normal job. Still not back yet. bitflipper, it actually sounds like a put a distortion pedal in the signal path. Lightly though. At first I thought it was my Tele, giving me some grief. Changed to another, cleaner one, and same thing. So then I suspected my new Fender Champion amp, then the mike, then the cables, and of course, then I swapped out the interface. I couldn't record without it being there. At that time, I was only suspecting what I was doing on the day, and nothing else I had already tracked. So, I solo'd everything, and realised my acoustic work was missing heaps, and slightly distorted. It's just the Tele made it more obvious. Then I realised how much trouble I'd had chopping all the bass tracks for this project, and went back and had a good look at them too. It was everything I'd tracked in the last month. Everything tracked prior to switching over to CbB was OK. And yes Noel, I opened the projects in Platinum, and all the new tracks had the same distortion there too. It is absolutely in what's been recorded. I do realise it's not the actual software causing it, but don't know enough to figure out what other things might affect what goes onto the disk. So thanks for the input. It means a lot.
 
I don't know what to think. I've uncluttered the drives, deleted and renewed drivers, changed the USB cable from the interface. Reinstalled CbB. I don't know at what point everything came good again, but all seems fine now. But it's left me very nervous. I'm about half through fixing everything and have the gent back in two days to finish off all vocals, so I can begin finishing up his album, then the next project starts from tomorrow. I guess I'm going to be more on the look out for any further problems hoping TO never let things get to this stage again. As you can imagine, no matter the reason, it's caused more than a little grief.
 
Everyone's given me things to think about and try to sort. I will keep trying to recreate this, because I want to know what's caused this too. Many thanks for the time given. very much appreciated. Dave.

bitflipper
Verify that it's actually distortion you're hearing rather than, say, crackling from short dropouts due to buffer underflows. Do you hear the distortion on individual soloed tracks, or only in the full mix? Can you see obvious clipping if you freeze a track with fx?

Only on solo'd tracks bitflipper. it's pretty hard to hear in the final mix. some of it anyway. But for country music, things like bass and acoustic, for me, have to as good as I can get them. No clipping evident, but I do try to keep to everything around -10db max when tracking. It's not digital distortion. Best description would be like a bad guitar lead. Distortion and frequency loss. 

GaryMedia
I seriously doubt that such a subtle data integrity problem with an SSD or HDD would arise because it's filling. The same operating system and hardware features that use the CRC and ECC as implemented for word processing documents and spreadsheets, is also in the chain for opening/closing and managing wave files. 
 
There is a sort of  'a-priori' data coming off of the converter on the way into the computer; there's no way to say whether or not that 3-byte sample has the right or wrong value, and we have to simply trust that the converter has done its job properly.  From that point onward, the data integrity mechanisms for the computer are working at every level of handoff between the I/O device, the CPU, registers, RAM, etc.  A problem anywhere in that group of functions will not present itself in a way that's confined to just the music.  
 

That's an interesting post GaryMedia. I've been having trouble with things like word, simply refusing to open a document, then no problem next time I turn on my PC. An email that would not attach a file, then after about 5 attempts, just suddenly worked. Just minor things that I ignore in general.
 
Is everything connected? Don't know, but it's food for thought. thanks..

Just to take CbB out of the loop and verify this was baked in (it should not be as Noel mentioned), drill into your audio folder with Windows Explorer and listen to those tracks with a generic media player.

CbB streams from the audio interface directly to disk, so if that original (not bounced) wav file has distortion, it is what your AI sent to the computer... Or even "baked in" it could be an issue with the AI on playback (buffers, drivers, etc. as mentioned above). Generic media player through another AI, or even an onboard RealTek, would help locating where this is occurring.

To apply best practices for troubleshooting. You swap out each component until you find the one that was causing the problem. You work your way from the front to the back of the signal chain. 

mettelus
Just to take CbB out of the loop and verify this was baked in (it should not be as Noel mentioned), drill into your audio folder with Windows Explorer and listen to those tracks with a generic media player.

CbB streams from the audio interface directly to disk, so if that original (not bounced) wav file has distortion, it is what your AI sent to the computer... Or even "baked in" it could be an issue with the AI on playback (buffers, drivers, etc. as mentioned above). Generic media player through another AI, or even an onboard RealTek, would help locating where this is occurring.

Thanks Mettelus. I've just done that, and low and behold, the tracks in the folder are fine. So, Noel, was indeed correct. I should have done that first up, but being able to record 'clean', under different scenario's sent me off on the wrong track, and I was panicking a little I must admit, and I  thought I had already 'proved' it was the recording.
 
So I've gone back to look at everything again and think I have found the problem, though I have no idea what causes it. It relates to something I posted a few weeks ago. Every time I insert a new bus, the console emulator is locked onto one present. I can't select either of the other two presets without removing it, and reinserting it. I also cannot turn the emulator on, or off. It's like its frozen. It's been bugging me, and is only something evident in CbB. So I changed the path from all tracks back to the Master, and everything is OK. Back through the bus, distortion. Turn off global Fx. No distortion. Turn off only the prochannel, no distortion. Turn it back on, turn everything else off except the console emulator, distortion. Remove and re-install the console emulator, no distortion.
 
I can recreate this by inserting a new bus, routing to that bus, and turning on the console emulator, which freezes until I delete it and reinstall it.
 
Mettelus. I owe you big time man. I've re-tracked a fair bit now over the last week, but I can pull up the original takes now if I want too. It's back to business now and into the final phase for this project anyway. New one starts tonight. Wish me luck....
 
Kindest regards to all for your assistance. Dave.
 
 

Glad you found the problem. I had a very similar experience  last night. 
 
I'm mixing an album and I use the Ample P bass lite on all bass parts. 
I make sure all settings are the same so once exported all songs will have the same bass level. 
One song the bass was audibly louder and peaking the Buss.  
I was going nuts as everything was the same, velocity, the volume of the GUI and track etc. 
 
I always put a Pro channel hi pass on the Bass buss and when I toggled the Pro channel off the level went down??
So I looked and found that somehow the console emulator was inserted and on?? I certainly never use that so don't know how it got there.  I will have to keep an eye on Pro Channel from now on. 
 

sock monkey
Glad you found the problem. I had a very similar experience  last night. 
 
I'm mixing an album and I use the Ample P bass lite on all bass parts. 
I make sure all settings are the same so once exported all songs will have the same bass level. 
One song the bass was audibly louder and peaking the Buss.  
I was going nuts as everything was the same, velocity, the volume of the GUI and track etc. 
 
I always put a Pro channel hi pass on the Bass buss and when I toggled the Pro channel off the level went down??
So I looked and found that somehow the console emulator was inserted and on?? I certainly never use that so don't know how it got there.  I will have to keep an eye on Pro Channel from now on. 
 

I'm removing all emulator's from my new project's template after yet more trouble. Maybe when the project is near completion and in the final mixing stage I'll put them back in. I do like the effect. But for now...gone...
 
All the best.