I know that some of you have experienced a problem, as have I, with Arturia's Oberheim SEM soft synth.  i.e. It cause SONAR X3e to blow up when trying to insert.
 
Arturia's recommendation is to roll back to X3d which I personal find unacceptable.
 
I was having a little troll through some of my works in progress and loaded a project in SONAR X3e which contains the SEM synth, which loaded and worked OK.  I consequently tried an experiment.  I cleared the project of every thing except the SEM synth saved it as a template and then tried to use the template to create a new project.  UIt worked.
 
Now I will not guarantee it will work for others and it is really not acceptable but if you want to give it a go you may find it will work for you.
 
As an aside Arturia tell that the problem is with the VST 3 version and not the VST 2 therefore un-installing the VST 3 is also a potential solution.
 
I hope this might help some of you.

Artura's stuff didn't work in X3d either. I bought one of their controllers a while ago and it came bundled with a bunch of soft synths, I ended up returning it.

I have had little problem with Arturia synths up until X3e andI fail to understand why such a problem now exists all my other VST's work fine it only the Arturia ones that are twitching. 

Wookiee
I have had little problem with Arturia synths up until X3e andI fail to understand why such a problem now exists all my other VST's work fine it only the Arturia ones that are twitching. 

even if you remove the vst3 versions? from what i've read on the forums, various vst3 plugs needed some special cake attention before they worked properly in sonar...

Seems its the VST3 Arturia synths that are crashing for me CWBRN-26631.
 
The VST2 ones seem to work fine but SEM, Analog Factory and Wurlitzer V are VST3 and all crash Sonar on insert. Now I have to work if I can install VST versions of these.
 

Further to the last post, I moved the DLLs in the 64bit VST directory to a backup location, Sonar then picked up the 32 bit VST2 versions and they work fine using bitbridge.

There are 64 bit vst2 versions of the 3 problematic vst3s, no need to use bitbriidge.  I can only confirm that the vst2 version of SEM works correctly in 64 bit X3E.

Glyn Barnes
Further to the last post, I moved the DLLs in the 64bit VST directory to a backup location, Sonar then picked up the 32 bit VST2 versions and they work fine using bitbridge.

Glyn and anyone else who is interested find the directory %system%/program files/common files/vst3 I think that's the correct route find the Arturia files Oberhiem SEM V.vst3 and rename it something like Oberhiem SEM V.vst3.NG.  For me NG meant No Good.  Rename all the Arturia VST in this directory similarly.
 
Start SONAR, let the vst Scan finish, open the cakewalk plugin manager, force a rescan of all VST's if you have personalised layouts open them and check that the plugin has not become greyed out if it has just select it from the right subsection and re add the plugin.
 
This worked for me earlier today I had no problem with any of my Arturia synths and I own the V-Collection.

Instead of renaming or moving the plug-in binaries, it should be possible to go into the Cakewalk Plug-in Manager and exclude the unwanted versions.

scook
Instead of renaming or moving the plug-in binaries, it should be possible to go into the Cakewalk Plug-in Manager and exclude the unwanted versions.

No does not work if you exclude the plugin you exclude both VST 2 and VST 3 tried that one.  The one thing I did not try was turning off the automatic replacement.  This off course has the knock on affect of applying to all VST3 plugs which is a little bit of a pain when it appears to be only one suppliers plugs that have a problem, well for me anyway.