Had similar problems.
Did JSGME unmod. Patched. Had crashes and loading errors. would not let me uninstall or reinstall. I musta manually edited something or other and forgot about it.
I manually deleted all the SH4 files and ran a registry cleaner.
Good freebee here:
http://www.ccleaner.com/
Then it allowed me to reinstall.
Patched, no problems.
Doom
vista 32bit