I've seen a couple of posts with similar issues, but I'm wondering if anyone has any idea what might be going on. I've been trying to get through to Cakewalk support for two days, but can't get through the infinite holds. I switched from X2 to X3 ( the latest versions of each) last week. X2 works great and has been for quite a while now with no issues recording or playing back (pretty much), but I can't record on X3 without experiencing crackles and pops unless I set my ASIO slider so high that it creates impractical latency for recording. It actually will crackle and occasionally completely drop out even while playing back a project. I have the exact settings I was using for buffers, caching, etc. when I was using X2. Also, the symptoms are the same with no plug-ins in use at all. If I go back to X2 everything works great again, For what it's worth, my ASIO slider is set to the number 4 position, which gives me 11ms latency. For now I'm relegated to recording in X2 and editing in X3. Not a huge problem, I suppose, but if I ever need to record some else on a song I'm working on in X3, I can't go back and open it in X2, so I'd be screwed. Any suggestions would be welcome.  Thanks guys and gals.

Actually you can go back to older versions and if there all installed on the same computer even your plug ins are shared. Only thing is Sonar will flash a message to warn you that the project was created on a newer version. Ignore it. 
 
I would try re installing X3 as something must be not adding up. Did you tell it during installation to migrate your old settings? 

What ARE your current Sample Rate and bit-depth settings, and your total roundtrip latency?
 
I suggest trying for a total roundtrip latency of at or slightly less than 10 milliseconds.  I saw you are reporting around 11 ms, but it is not clear if that is input, output, or total roundtrip.
 
Also, what sort of plugins are present in projects where you are having these troubles?  (32-bit, or 64-bit ones that use look-ahead processing or loads of CPU?)
 
What are your settings for Playback I/O Buffer Size and Recording I/O Buffer Size?  If they are at the default of 250 k, or 256 k, try setting those to 500 k or 512 k.
 
Bob Bone

Sample rate 44.1 / 24 bit
 
11.4 ms round trip
 
Playback I/O 256  Recording I/O 256  - already tried 512 with no difference at all
 
I removed all plug-ins from the project and still had the crackles and pops in X3. In X2 I use a couple of UAD-2 plug-ins as well as a couple of T-Racks plugs and Aether 2C reverb while tracking with no issues.

BTW, my interface(s) are two VS-700Rs.

Did you migrate your settings? If yes then there is obviously something wrong with your x3 install. 

Is it happening for all projects or just one project? If its just one project, then its a simple ASIO or WDM driver adjournment or you are clipping.
 
If its happening for all projects, maybe its an issue with your sound cards not being set as a slave and master. when you use 2 cards, one needs to be set as a master for the clocking, otherwise you will hear artifacts
 
CJ

Thanks CJ, it happens in all projects in X3 - new or opening previous X2 projects. Interesting that the sound card settings are identical to what I am using for X2 with no problems. It does act and sound like some sort of clocking problem. VS700R #2 is word clocked to VS700R #1, maybe there's a potential suspect there somewhere...?