The main problem I have with this approach is having to open each project that uses IK multimedia plug-ins and replace the plug-in and locate the sounds I used. Some of them uses several sounds. I have tried to avoid using these older plug-ins because they are 32bit. Most of my sounds come from NI Komplete, Dimension Pro, Rapture Pro and some AAS and Linplug stuff. 

timp410
The main problem I have with this approach is having to open each project that uses IK multimedia plug-ins and replace the plug-in and locate the sounds I used. Some of them uses several sounds. I have tried to avoid using these older plug-ins because they are 32bit. Most of my sounds come from NI Komplete, Dimension Pro, Rapture Pro and some AAS and Linplug stuff. 

Yes bro. I know the feeling. Have you submitted a support ticket? I will try to install ST 2.5.4 later to see if any problem occur. Been using ST3 fo a while now without any problem. I think you should try ST3.

Yes indeed...
"Thank you for submitting a problem report. You can track your report on our website here: CWBRN-33315"
I have been thinking about purchasing ST3 for some time now. I have so many expansion packs for ST2 that I have purchased over the years, it only makes sense. I just could not justify it since the current version I had worked fine.

FYI, your email address is embedded in the link in msg #23

Sampletank 2 and it's clones (Sonic Synth 2/etc) all fail for me just as reported here.  My older NI 32-bit plugins seem to work though.
 
Sampletank 3 does seem to work but that doesn't help older projects.  ST2 was fine before the update.
 

Sampletank 2 runs fine here under Everett, as long as I run Sonar as administrator - otherwise it fails. It's been like that for some time now though.

Plug-ins made when XP was the current OS may access parts of the registry which in newer OSes require elevated privileges. This is why running SONAR as administrator or modifying the registry is required for those plug-ins.

ST 2.5 and older always hadkxed results with Sonar X series amd beyond 74 bit versions. One of the reasons there was so much hoopla on these boards for awhile was the delay releasing ST3 made ST libraries useless for a lot of people. I would upgrading or trying in 32 bit.

If you own pre ST3 there was 64 bit version. I know I used it. Why are you using 32 bit?

Sampletank 3 was the first 64 bit version.  There are no 64 bit versions of Sampletank 2.
 
For new projects Sampletank 3 (which is only 64bit) works just fine.  But opening older projects requires a working Sampletank 2.  Even if you just want to see what the settings are so you can duplicate them in Sampletank 3.  If you can't load the project it's really hard to "upgrade it"