Engerek01: That's the issue if my memory serves me correctly. There was a bug that was causing that error message for disks that are beyond 1TBs?I am not sure but you can try installing the game to a smaller size partition (if you have one) and see if that solves the problem.
scientiae: Yeah, the address (in the hard disc) is too big for the (old) index software. (Another example was older (pre-32bit) versions of Windows could not access more than 2GB of RAM.)
If this is the reason, you could buy a smaller disc to install (on your network); otherwise partitioning your drive will work. (This can be done without damaging any data already on the disc.) If you don't know how to partition, you'll have to hire someone to create a small partition for the drive. (It's easy, but it'd be a brave tech support that would tell someone how to do it over a discontinuous medium, like a forum.)
Cue brave tech support …
In my case I don't think this is the issue. It used to work on the current disk I'm using. I didn't play for about a month or two then came back and now I can't use quick save.
I'm not sure if it was something I did to my computer or if maybe an update to the game cause the issue or maybe even a combination of both.
Anyway if anyone has any other ideas on how to fix this please let me know. It's getting very frustrating.
One other thing is that both BGEE and IWDEE are working just fine.