That sounds like you installed the 32 and 64 bit versions in the same place, or at least a .dll that should have 32 and 64 bit versions has got shared between your 2 installs.

Hmmm that could be an issue! Although I am sure I never mess with the location of the install directoires during setup! In fact on closer inspection it would seem all the 64 bit stuff is in the correct Cakewalk folder inside the c/Program files dir, where as the 32 bit stuff is under c/program files (x86)
 
Although I do think maybe your on to something with a shared dll ?? What would be the best method to fix this? uninstall and then re-install? I have heard some replies saying uninstall doesnt fully uninstall sonar?
 
I dont know if this is worth mentioning or not, as it may seem completely off topic, but I am currently in a tech conversation with IK Multimedia, and have been for over a week regarding my new Sampletank 3. You see when I load up Sonar 64bit (when it works) I cannot make it FIND sampletank 3 in the plugins manager! I have tried EVERYTHING.......I Have made sure the plugin manager is looking in the correct folder where the sampletank3.dll is, but it finds everything else EXCEPT sampletank 3
 
It runs fine in standalone, but my sonar 64bit just wont find it!
 
IK Multimedia are out of ideas! and so you guys wouldnt think that this current sonar problem is connected in any way would you?

The symptom sounds like your automation DLL got unregistered. To manually register it open an admin DOS box, navigate to the folder where the CW**auto.dll file is found. Typically "C:\Program Files\Cakewalk\Shared Utilities". On a X64 system running 32 bit the location would be: C:\Program Files (x86)\Cakewalk\Shared Utilities". 
 
Then type this (replacing the ** by the appropriate version number that you see for your product) :
 
regsvr32 CW**Auto.dll
 
This should reregister the dll.
 

Thanks Noel! Just looked and I have 3 files, which one should I apply changes to?
 
cw13auto.dll
 
CW85Auto.dll
 
cw100auto.dll
 

Just did it to all three dlls and unfortunately the only sonar version that works is the 64bit, but the 32 still wont load, Doh!

I seem to remember I couldn't get both versions to work so what I did was installed my old Sonar 7 32 Bit. I would use that to open my old projects. Just an idea.
And take note that there is increadble pricing on the new Sonar for ALL Sonar users. 
An 8.5 users will be more than well equipped using the new Pofessional version.  
And if you go for the monthly rates you can sort of try before you buy. 
 
I own an older version of Sonar  
Artist = $49  
Professional = $99 
Platinum = $199
 
 

The 32 bit files would be in the C:\Program Files (x86) folder.

Hey chaps! After so much frustration I have decided to remove everything related to cakewalk and then re-install! I just wondered if Uninstalling is enough? How can I completely remove everything and start again? Somebody mentioned registry keys? How would I erase them?

hey chaps! So I uninstalled all my sonar programs and then Reinstalled the 32bit version! BINGO it works fine!.......Then I proceeded to install the 64bit version! All the installing seemed to go fine, installed correct patches etc!.....Then afterwards I attempted to run the 64bit version......on double clicking the shortcut it placed on the desktop, I was greeted with this message "unable to execute file createprocess failed code 740"
 
So instead I went into the C:\Program Files\Cakewalk\SONAR 8.5 Studio folder and double clicked the EXE.... Now that actually worked and loaded up the 64bit version! However after scanning for the sampletank 3 dll, It STILL did not find it! Arghhhh
 
I then attempted to run the 32bit version of sonar, by going to C:\Program Files (x86)\Cakewalk\SONAR 8.5 Studio and double clicking the EXE.......but guess what? Splash screen shows up for a sec and then disappears and nothing happens! Kept my eye on the windows task manager and sure enough as soon as Sonar32bit show up it disappears!
 
It would seem that installing the 64bit version something messes up the 32bit version! Arghhhhhh

Quick update guys......Uninstalled everything completely......Removed all registry entries.....restarted fresh and began installing Sonar 64bit.....Added updated to lastest patches 8.5.3
 
Loaded up Sonar 64 bit, YEP it works! :)
 
To my surprise, after a scan in the plugin manager it FOUND sampletank 3 as well yay!
 
This time round I made sure the only plugins that the 64bit Sonar was looking at were 64bit plugins!
 
Now its time to install the 32bit Sonar (So I can have access to my old mixes)
 
Installed perfect, Then updated to lastest patches, and then ran the program! YAY! sonar 32 bit works as well!
 
Closed down Sonar 32 bit, and tried to load Sonar 64bit......... NOPE! Splash screen attempts to load then nothing!
 
Tried 32 bit version again....Yep works fine
 
64 bit, Nope! Refuses to load!
 
Restarted PC, went straight to the 64bit Sonar and NOPE still nothing
 
....... About to set my PC on fire then huddle on the floor in the corner crying!