Doktor Avalanche
Did you run chkdsk /r
?
What are the error messages in event viewer?

Ran a chkdsk and found no problems. Did not see any event for Sonar although I may be reading it wrong. It seems to start the Our of Memory message as soon as the vst scan starts so my guess would be that is where the problem lies. May have to do a total clean reinstall and move all items out of the vst folder to somewhere else and do a path to that folder. Wish I was a bit more knowledgeable about computers may be able to understand this better.

Start Sonar in safe mode and/or rename the plugon folder I suggest so plugins don't load.

If that works maybe you can nail down a problem plugin.

Hi Novasonic.  Were you able to get this issue resolved?  I started having the same problem on 2/15/16.  I would simply try to launch Sonar Platinum but would get exactly 25 "Out of Memory" error boxes with the system bell chiming each time.  After 25 errors, Windows gives up and shuts down Sonar but the Sonar Start screen persists and must be shut down manually through the task manager. Following tech support instructions, I've:

1. re-installed the C++ redistributables
2. performed a complete uninstall and re-install of Sonar platinum.

Neither of these actions resolved the issue.    For kicks, I installed my old copy of X3, and that still works.
I don't think it's a real memory problem, but rather a file corruption within windows. I'm running windows 10 x64 on an Intel Core i7 CPU with 16GB RAM.
In the event viewer,  I get the following error every time I try to launch Platinum
 
Faulting application name: SONARPLT.exe, version: 21.12.0.36, time stamp: 0x56aa51ca
Faulting module name: SHELL32.dll, version: 10.0.10586.103, time stamp: 0x56a84d77
Exception code: 0xc0000005
Fault offset: 0x00000000001771d7
Faulting process id: 0x1a10
Faulting application start time: 0x01d16baf92c3b23a
Faulting application path: C:\Program Files\Cakewalk\SONAR Platinum\SONARPLT.exe
Faulting module path: C:\WINDOWS\system32\SHELL32.dll
Report Id: 5eca3942-93b9-4fcc-9f62-6c69f333bced
Faulting package full name:
Faulting package-relative application ID:

If you were able to get this resolved,  please let me know how.
 
 

Make sure you've disabled the automatic plugin scan. If turning that off makes your problem go away, run a scan manually and see if those out-of-memory errors return. If they do, check the search paths and see if there are duplicate or recursive references, e.g. a path that includes another path that's already included.

Is there a way I can disable the plug-in scan externally (any parameter that can be toggled in a configuration file)?  Right now,  I can't even get Sonar to open, so I can't get to the Preferences or Plug-in Manager.

When SONAR appears to hang on startup often it is either waiting for user input to a dialog hiding behind the main screen or waiting for a reply from the audio driver. The former takes a user response the latter usually requires a reboot.
 
FWIW, the scanner schedule preference is stored in the registry key VSTScanScheduling under HKEY_CURRENT_USER\SOFTWARE\Cakewalk Music Software\SONAR\Platinum
 
0 = Automatic Background Scan
1 = Scan On Startup
2 = Manual Scan

Enter Settings / Audio / Driver Setup and on 64-Bit Dual Precision Engine Disable 64-bit
Note: It worked in my case, I use 32 bit system
Hope this helps. Hug!
Greetings from Brazil!