No, I'm running the default game, clean install, and AFAIK those savegames were not saved from mods (there's no mention of mods on the download page).
I did find a workaround. If I delete gta_vc.set and start the game with default settings, I can load the savegames. Then I manually reset my controls/audio/video/etc every time I want to play. This sucks, but it works. The only thing I can't change is screen resolution (can't be changed while playing), so I have to play @ 640x480 & 16-bit color.