After installing Music Creator 6 on my Vista machine, the machine crashes when starting Music Creator with the message BAD_POOL_CALLER.  Although I have sent emails to support 7 days ago I have had no reply. Anybody help please?

Welcome to the forum.
 
http://answers.microsoft.com/en-us/windows/forum/windows_vista-system/badpoolcaller-0x000000c2-blue-screen/d6280433-ff90-46ec-8d8c-ab8b3c6a87bb
 
Hope that helps. Good luck.

Did you buy the MC6 version that is Vista compliant?  Apparently there are 2 versions depending on your OS.
 
http://www.store.cakewalk.com/b2cus/ProductInfo.aspx?productid=10-CWMC6.00-30E
 
If you do not have the Vista version, that could be the reason it crashes, assuming that nothing else crashes it of course.
 
If you have the wrong version, I'd place a call to them and see if they can swap the versions for you.

MC6 is based on X1 which directly supported Vista.
MC6T is based on X2. Although X2 dropped Vista support, many users still successfully ran X2 on Vista. There were no reported compatibility issues running X2 on Vista. X2 would even run on XP until the X2a patch. Still X2a ran fine on Vista. X3 runs on Vista, the only reported issue was a problem with the plug-in manager which was fixed in a subsequent patch. Even though Cakewalk does not officially support Vista with X2 and MC6T, I do not believe the problem is a compatibility issue with the OS.