Is there an easy way to find out which plugin failed during the VST scan. I have one which causes "Cakewalk VST Scan has stopped working" to pop up. It still finishes to scan the rest of the plugins, so long as you don't hit close program or close out the box till it finishes. Debug doesn't do anything except closes out the rest of the VST scan.
Cakewalk Sonar X-2 Studio

It is a bit of an iterative process (i.e. move all the plug-ins out of the scan path and add them back in until the offender is found) but it should continue to happen. You may want to check Preferences > File > VST Settings and make sure "Re-scan Failed Plug-ins" is unchecked. Also "Re-scan Existing Plug-ins" is normally unchecked too.

Also, if you have many plugins, try limiting the scan down to only 32-bit plugins or 64-bit plugins. This bolsters the fact that separating 32 vs. 64-bit plugins is a good idea. It aids in troubleshooting and sorting on the back-end.  In Sonar, however, it's seamless; and you build your plugin list using the Plugin Layout tool to your liking.
 
Some of the plugins that can be annoying in Sonar are sometimes the SynthEdit variety.  Some are coded very poorly! I had to ditch my entire collection of 'm' free plugins, e.g. mComp, mPhaser, mFilter, etc., because they all did not work using BitBridge.