Hi,
I'm running on W7-64 and it works but initially I had trouble as well. Though I don't recognise the error you've got.

When using 64bit versions you must use MPASM as the assembler, in MCSP select View->Compile and program options, select the Assembler tab and tick the box for MPASM (if you haven't already), then make sure it points to the correct location.

Second, (this may not apply depending on the version of MCSP that you've got) I had problems updating my MCSP online. Turned out I had to run MCSP in XP compatibility mode while running the update and then switching it back to normal mode. (I'm now on 3.0.0.5 with PBP 2.60).

Also, try running MCSP with administrator rights.

I hope you'll get it going!
/Henrik.