Oblivion stuck, frozen or whatever may be

[Caesar Quintus]

I encountered a strange bug (or glitch) extremely annoying.From time to time, it seems that I can't activate anything in the world of Nirn. I first observed the bug when flames (from torches, chimneys, external lamps on walls etc.) remained static (wouldn't sway any longer). In this state, I can't activate anything which normally I could activate, ex: gates(in Ayleid ruins) which are locked won't open when lockpicked, doors locked with keys won't open when using keys, sigil stones (in Oblivion) remain stuck thus I can't exit and close the Oblivion gate, I also cannot trigger the realm of Shivering Isles (after the dialogue in the first chamber, I got stuck in there) etc. Also, if I quicksave (F5) the game in that state, I cannot reload the scene.Needless to say how annoyed I was when my last save(with save command) was 7 hrs before and the last autosave and quicksave did not load.
I tried uninstalling and reinstalling the game and the bug persist.
I have installed Oblivion main, SI, KOTN all official plugins and different mods (not hardly modded).I am also using OBSE, OBMM and BOSS.
Any ideas from where this bug could appear?
Please help.
PS. I cannot play from the scratch because my character is lvl 40 so I am forced to use the last saves.