I installed the new update and had all sorts of problems. I am running Windows 7 64bit. Once I installed it I had a total nightmare with my plug ins list. I have never before come up against the CLSID problem before but every time I tried to open a synth or FX I had it in spades. And weird random things like renaming dll's. My Trillian plug in had been renamed for instance. I could only open one instance of any Waves plug in. I had to reboot if I wanted to open a different Waves plug in. If I opned T-Racks CS standalone it would then crash my sound card drivers and I would have to uninstall and reinstall. Anyway I uninstalled and reinstalled X3 up to the X3 b update and now everything seems back to normal. Mental weirdness. Any one else had any totally random weird problems with X3c?

There have been a few problems with X3c.  Use your system restore to go back to your previous version.  It takes about 10 minutes or so.

Thanks Lynn, I have done that now. Fingers crossed all seems to be ok again. Very odd.

I had to roll back to x3b as well (using system restore).
 
In x3c some of my projects would just lock up (had to close them using task manager), some worked normally, but most would play some tracks but not others.
 
The tracks that would not play any audio would give a loud pop when I would first hit play and the meter for that track would show 9 db in the red.  If I deleted all pluggins and prochannel effects sometimes it would work for a while.
 
I tried tracking it down to specific plugins, but it was too random (besides a couple voxengo plugins, Kontakt, and Guitar Rig,  I'm using mostly Effects from Sonar).
 
This is on Windows 8.1 AMD system with a MR816x using AISO
Buffer settings, or switching to WDM made no difference.

It's amazing but I haven't experienced any of the problems people have been talking about with X3c. Funny to think how different our experiences all are. 
 
As for your plugins being renamed, you can set the naming convention in your initialization file. See here:
 
http://www.cakewalk.com/Support/kb/reader.aspx/2007013302

+1 sharke...not one issue on my system either. Everything ran exactly as before, I even managed to import some older CWB data with no issues! I suspect (and all due respect to posters) that perhaps the issues are with systems rather than CW. What else would explain the many differences, and why the vast majority of upgraders have no problems. Stands to reason doesn't it - I mean there must have been thousands of upgrade downloads already, but, relatively, only a handful of folks with issues.
 
And I guess it is human nature to not fully admit what someone has tweaked without knowledge, to avoid embarrassment. I come across it all the time in repairing PC systems for folk. They swear black and blue they have touched nothing and done nothing, but it always ends up with a sheepish admission usually after a couple of hours of problem hunting and elimination . Not saying that is the case here, but anecdotally, it is remarkably similar.
 

joden 
And I guess it is human nature to not fully admit what someone has tweaked without knowledge, to avoid embarrassment. I come across it all the time in repairing PC systems for folk. They swear black and blue they have touched nothing and done nothing, but it always ends up with a sheepish admission usually after a couple of hours of problem hunting and elimination . Not saying that is the case here, but anecdotally, it is remarkably similar.
 

I would be glad to admit messing up my system:-) besides setting things up to use a high performance power plan, and making sure I'm not having cores parking on me, this is a clean install of Windows 8 from just before x3 came out.  I since have updated to windows 8.1 with no problems.  X3 has been the best version of Sonar for me up until this patch.
 
I might have been sleep tweaking or something - if I remember anything I might have done, I will definitely update this post.  The only other thing I have done is use ccleaner to clean the registry, but I think that was before the windows 8.1 update.
 
I once got into a problem with tweaking things (turning off services) that messed up how Sonar handled the naming of plugins, so on this install, I stayed clear of that stuff.

One more small piece of info - The projects that gave me the most grief on X3c were older projects that I started from templates from x1 days.  I don't know if this has any bearing on things, but my newer projects were the ones that worked fine with X3c.

Just a thought - did you reinstall Sonar after upgrading to Win8.1? If not, might be worth a try.

Cheers, Peter.

PeterMc
Just a thought - did you reinstall Sonar after upgrading to Win8.1? If not, might be worth a try.

Cheers, Peter.

I didn't try that - Ill give it a shot some time in the next couple days.