Thanks, Richard! I finally got a reply on the .NET Framework forum--ver3.5 is fully cumulative (unlike previous versions), so all I had to do was install that! WHEW! It's so AWESOME not to have to go through that NIGHTMARE install again like I did last time!
Before, I had to install 1.0, 1.1, 2.0. 3.0, AND their respective service packs, rebooting after each, in order to get it to work.
I think I had one of the later service packs not install properly, so I had to uninstall EVERYTHING, run a .NET Framework cleaner tool, and start all over again!