When I try to simulate building performance in version 3.64, I get "Error:
1 standard file writing errors occurred".

How do I go about getting around this problem? There should be no reason I
can think of that the program can't write to disk.

This does not happen if I start a new project, accept all the defaults, and
simulate it, as a simple test.

The project in question was opened from a thumb drive, and then "save as"
to the hard drive. Is there some other secret component that has to be
copied to make this work?

I'm running windows 7 if that makes any difference.