So... 
 
What about testing an old project by "replacing" the offending vst on the track and see if it starts working... This could be very manual but also could give clues to Cake about what is happening.I had a kind of similar issue with a bus that would not play until I replaced it... IHTH

Hey Dave! Nope they arent cakewalk plugins they are things like BFD and T-Racks, Unfortunatley I was unable to have both installations of 32 bit Sonar and 64 bit Sonar on my system at one time (see my posts last week) I really wish that was possible! Can you just confirm if you are able to have both a 64bit Sonar AND a 32bit Sonar on your system at the same time, meaning you can load each one up whether you fancy it?
 
Hey LunaTech! Yep I have tried that but unfortunately its the actual settings that I am desperate to load! So even though I CAN just replace that vst with the working one, I am unable to remember all the individual settings etc

try to run as administrator.

Yep already doing that bud! Is it normal to not be able to have both 32bit and 64bit on one system at any time? I find that once I install the other one it cancels out the working one and refuses to load

I have so yes, well I am.. There is a bit bridge that is suppose to bridge 32bit in 64bit mode I have had a hard time getting all plugins to work in x3pro. I have gotten a bit bridge errors with X3, I'm not that far into platinum yet.. 
I kind of think it has something to do with Sonar 8 32 and a conflict with 64 bit X3, just what I think...
I have been working on this problem for at lease to months... sometime the VSTs work sometimes they don't and the problem is for me with IK but now after installing platinum 64 basically over 32 bit X3. everything is works except old cakewalk plugs.. I don't have any BFD plugs ...  
 
 
update: I just tried to open a sonar 8 CWB project into platinum and I got the same error... even though I have all plugs installed now it still says they are missing... 

Thats so weird because when I install sonar 64bit it works fine, but then I install 32bit Sonar and that also works fine, but when I try and load up 64 again it just wont load up

I don't know. I have uninstalled and reinstalled from every point including re formatting the hard drive.. once every two weeks since October trying different setups. but I really believe that for your problem, well mine to... you can't just import Sonar 8 projects into x3 or platinum and read and replace some plugins...

Deanahguitarist, I know this may sound crazy but hear me out. Sonar is very odd at times in how it sees plugins. Look at your plugin list, whether its default or a custom one you made. Load it up and take a look at where the plugin used to be. It's probably a italic or "ghosted" inscription of the plugins name (which means it is "missing" in some way). Now, simply add the so-called missing plugin back to the list, in that location of the list. Save the plugin layout, close sonar, and open your project again. Do you still get the msg?

Hello,
 
Question, Are your 32bit and 64 bit plugins  in completely separate folder locations?.. I have found that when I only use my 64bit version of plugins and Jbridge the 32bits that I absolutely must have, my stability has increased. My point is that having them all in the same place seemed to cause me issues with the plugins and stability.. So, My suggestion is that once the plugs are separated into their folders and the respective versions of Sonar only pointing to their versions (32bit, 64bit) of plugins. I am wondering if it is not possible to then go to the 32bit version of Sonar to see if the settings are retained and then making those adjustments in the 64bit version.. Just processing out loud... IHTH....

The problem is with the bit bridge and how it saves or changes the plugin data somehow with in a project.. not a problem per say.. just the way it works.... If I take a x3 project and open it up in Sonar 8 the same thing happens...
Cakewalk may want to look into this but under the circumstances with everyone ignoring me and now for what I have no idea... well whatever...
 
peace