Try installing it outside of the Program Files folder. The save file issue is probably because Win 7 doesn't give permission for those applications to write data in certain places.
Right, that's why running it as an admin works.
It doesn't seem like you read my question very closely. I was asking if running the game without permissions caused any known issues. That's because I had already started the game and didn't want to start over. (Planescape: Torment, for example, caused no issues for me when run without admin privileges.)
What he means is, installing it out of program files folder makes it so you don't have to play in Admin. I've had this problem, in the form of my Fallout games crashing when I tried to save (along with my computer), but they got corrupted in the process.
P.S. To the guy who suggested the UAC thing, what is that?
P.P.S. Here's an example to this problem...On some OS, trying to mod certain game folders won't work because you don't have permissions to edit it(Which is why if you try it, it will ask you if you want to or not.)