To which game do you refer? Nehrim? Arktwend? Myar Aranath?
Maybe it is a problem with your mouse drivers (if you aren't using the default ones). Otherwise, you could delete (or move, to have a backup) the configuration file (for Nehrim: oblivion.ini) which is located in the same folder your save game folder is. By default this is:
"C:/Users/*yourname*/Documents/My Games/Oblivion"
If this doesn't help, you could try to reinstall the game (backup the saves, of course!...although they shouldn't be deleted if you don't choose to).