ok, update.
first off, i have NO idea what caused the change.
in short words, i can open the projects just fine now.
the only changes i made today were switching to background services rather than programs in the windows system panel (you know what i mean), and swapping out the firewire cable for a new one. btw, this solved my audio errors, so i'm starting to wonder if the cable was actually the culprit all the time.
so, the only stuff that's not working anymore (aside from reaper having lost all my shortcuts and my custom theme.....) is
a) kontakt/SSD3 requires new activation.....sucks, as last time was a PITA.
b) i can't open pod farm in a new project. it works just fine in my old projects, but it doesn't appear in the fx list when trying to add it to a track.