remove some of the many mods?
I had some problems with Oblivion some what recently made me have to go through clean installations a lot...I know guy, it svcks doesn't it? I had to do it...well I lost count but last number I remember was 6, so we can safely assume there had to be atleast 6 reinstalls.
that is:
Uninstall Oblivion, delete data folder, delete my games/Oblivion folder (while preserving my save files)
Re install Oblivion
Re install Shivering Isles
install patch
install mod utilities
install mods.
Becuase I ran this process so many times, I realize about 1/2 of the mods I used were pointless or stupid or just not worth taking up space or effort, so I removed them. So, really, consider going through the mod list and thinking carely if it is really worth the effort and another .esp moving you closer to the 255 limit. Right now I am a little above 100 mods each carefully thought out if they are neccessary or not. (plus they are all stable mods and have given me no problems, so this limits the frustrations that also comes with having a bunch of mods such as your case or just trying to disect which mod is the problem child)