SW2011SP0 on XP-64.

I have two hard drives in my computer (C drive running WinXP and SW2011SP0 and D drive running WinXP-64 and SW2011SP0-64).  After a reboot on the 64-bit side, when I try to run SolidWorks-64, the splash screen comes up and SLDWORKS.exe appears in Task Manager, but both disappear after a few seconds and nothing ever happens.  If I then navigate through Windows Explorer to the 32-bit exe on my C drive and run that file, SLDWORKS.exe *32 appears in Task Manager and the application starts fine.  Once fully loaded, closing the 32-bit version and retrying the 64-bit exe again works fine.  It seems I can't run the 64-bit version without first starting and then closing the 32-bit from the 64-bit OS.