So I'm having a problem here, it happens at random, and I don't know what could be causing it.
If I close it and open it again it'll usually fix it temporarily, but it just gets worse the longer I play and the more cells I enter/exit.
I'll post these in order of playing....

http://i361.photobucket.com/albums/oo60/Yevic1992/General%20Oblivion/ScreenShot176.jpg
http://i361.photobucket.com/albums/oo60/Yevic1992/General%20Oblivion/ScreenShot177.jpg
http://i361.photobucket.com/albums/oo60/Yevic1992/General%20Oblivion/ScreenShot178.jpg
http://i361.photobucket.com/albums/oo60/Yevic1992/General%20Oblivion/ScreenShot179.jpg
http://i361.photobucket.com/albums/oo60/Yevic1992/General%20Oblivion/ScreenShot180.jpg

Any ideas?

Maybe you're starting to run into that 300-400 .esp/.esm/.bsa limit. It can cause fairly random missing textures like that :shrug:

Video card overheatimg?? :huh:

Really?
Interesting, does that still count if their not activated?

I don't remember getting high before reading this post...but why are those pictures such a trip?

I would say it could possibly be similar to my "black plague" issue...but I called it black plague because my textures went black instead of the normal hot pink...I doubt they are related, but it is possible.

For me, I experianced similar results where textures would magically disappear and become just a black object, and it got worse and worse as I played.
However, people who helped me with that assumed it was just an overheated GPU, in your case I doubt that is it. Since things automatically restore after quitting and restarting Oblivion. (In my case - though Oblivion textures were restored on restarting Oblivion immediately after quitting out, it wouldn't take but one cell change before things were back to normal)

hmmmm....I think it could help others if you post an LO

Yes. It's why Wrye Bash's "Ghosting" feature exists. It amends .esms and .esps with a .ghost extension when they're not active so the game doesn't recognize them as its files.

You have reached the file cap in your data directory (which seems to vary by user ....its between 300-400 for sure). I had the same issue when I had 384 files (esm.esp.bsa) loading. I cut that down to under 350 (by merginhg esps etc.) and the anomalies went away.