Had a recording session on Windows 10 this past weekend. 18 tracks at once, and many overdubs. No issues with Windows 10. However, I did have a weird Audio Drop-Out Toaster alert. occur frequently when two Projects were open, and I was going back and forth between them. This would happen, even after I disable the Audio engine.
 
Aside from that, smooth sailing!
 
For you Windows10 users: Get an SSD. It does boot slower than 8.1, and sometimes opening Sonar projects is slower in Windows 10 by my tests. So, an SSD drive will help.

Were the two projects different sample rates - I think someone else posted about something similar.

dwardzala
Were the two projects different sample rates - I think someone else posted about something similar.

Actually, yes, they were. Thanks for that thought.

It would be great if someone from Cakewalk would notice this particular problem.
 
This also happens with two projects of the same sample rate. It has only happened since platinum - doesn't happen in X3 on the same system with identical drivers.  It also happens on Windows 7, so it is not OS dependant. I have also reproduced it on 2 different systems with different interfaces, so it is not exclusive to a particular driver. Despite having spent a very long time trying different settings, eliminating plugins etc, I am yet to get any closer at all to the cause. I have just gotten used to hitting the space bar 3 times when switching between projects!
 
Some people report a noise like a short sample looping or buzzing when restarting playback after switching between projects, others the audio dropout toaster popup. I've had both.
 
There is a thread about it in the depths of the problem reports somewhere, I posted a thread back in December, and a couple of other threads have come and gone as well. It just doesn't seem to be quite common enough to get traction on the forum:(
 
 
 

I think Noel mentioned in another thread that the audio engine pauses "momentarily" so the interface can adjust to the different settings in a project.  That is what is generating the drop out "toast."
 
This obviously doesn't explain same sample rate issues. 

And as far as sample rates, I did notice that the sample rate shown in the Control bar does not always reflect the sample rate configured in Preferences. That makes sense if the project is a different sample rate than what's configured for inputs, but how does this affect the sample rate the project has after a 44.1Khz project records a 96Khz sampled input? How does clocking not cause issues? This used to be a problem that didn't allow the Recording to start.

I just started recording projects using 48k sample rates. What I found is that there seem to be conflicts between SONAR and Windows that sometimes require manually altering the sample rate in the Windows Sound dialog to whatever sample rate SONAR needs to use for the project to be opened. And I also found that when switching between 48k and 44.1k sample rates in SONAR projects, I have to close SONAR and reopen it in order for SONAR to "catch up" with the fact that I changed the sample rates in the Windows Sound dialog. It seems one MUST change the Windows sample rate to whatever sample rate SONAR will play.  I spent several hours chatting with tech support for my Focusrite sound card about these issues since their software mixer also figures into these parameters.  But their mixer picks up almost immediately the sample rate change in Windows.  I'm wondering why SONAR takes so long to catch up.  I'm on Windows 10 by the way.
 
I cannot comment on audio drop outs as I started having them only last night and I have no idea why. It just happened in the middle of playing back a 12-track project with 2 MIDI tracks, 10 audio tracks and about 8 effects plugins - not very much at all for my system.  I sent the 2 crash reports to Cakewalk as requested.

I am confused by your statement of Windows Sound dialog.  Do you mean the ASIO panel for your focusrite?

Dave - No I mean when one right-clicks on the speaker icon in the Windows task bar and selects "Playback devices" for example. If you then select the device for your sound card, click Properties and then the Advanced tab, that's where one changes Windows 10 sample rates.

That's why I am confused - if you are using your Focusrite interface, why would you be changing sample rates in your windows devices?  Granted I am not familiar with the Focusrite interface, but I would think that you would be changing the settings there - not in Windows.  I don't change my Windows settings at all.