To me that sounds like something seriously messed up your your bsa's.
I have no idea what could cause that, if you really didn't change anything affecting the game's files.
The only thing you could try, although i don't know if it will change anything, is to delete oblivion.ini
(should be in my games/oblivion) and let oblivion/nehrim restore it from the oblivion_default.ini.
Backup your ini, just in case.
Also you could upload your last regular save (not the quicksave) so we can try if they still work on other pc's.