Try renaming it something other than zip. Try calling it like db2 or something.
To debug it from the source code, you have to search the source code for "error.sim". In that function, near the top, is a section that will say "on error goto errorsim" or something like that. You need to comment it out...
Anyway, dispair not! Later on I'm going to set my computer up as an FTP like I did in the summer, and you'll be able to just upload sims directly onto my computer.