LJB: Any chance you have changed your sampling rate? I changed mine and though Sonar itself didn't have an issue some plugins were not happy at all about the change and it took me quite some time to get everything back to 'happy'. Kontakt seemed to have issues and Scuffham S-Gear were the worst ones I saw.
 
Regards,

Another reason I never changed my sample rate.  Thanks Mike that is a very good tip. 

John: I wouldn't have changed mine either but I had an opportunity to work with video, so 48k it was. Oddly I was going to change it back to 44.1 after the project but I asked around on this forum (forget which topic) and didn't really see any downside...until I started importing templates and opening up older projects. I laugh now but at the time I was really not having a good time at ALL.
 
Regards

I just went through that trauma too, when I changed to 48 to match someone else's setup.  Plugins were PISSED.
 
I chose to go back to 44.1 at the end of it all, and am quite happy working at that rate.
 
Bob Bone