Quartus 8.1 Freeze On Startup / Nios IDE / Uninstall / Reinstall

Hello,

We're using Quartus 8.1 full version for a very old project. I was working in the Nios IDE today when suddenly the C code stopped compiling. I have been using this computer and configuration for quite some time. Yet, when I clean the syslib and main project, and then recompile, the computer hangs on "rebuilding make files (1%).

I've tried uninstalling the tools, and reinstalling them to no avail. Now, when I attempt to run Quartus 8.1, the computer hangs at the "Initializing" screen with the progress bar about75% done.

I'm guessing a file has been corrupted, and needs to be removed after uninstalling. Any ideas where this file might be located?

I was able install the same tool-chain on another computer, and get the project to compile.

All computers are Windows 7, 64-bit.

Thanks.

Brian