Open up operaprefs.ini (in the profile folder) and look for "Level Of Update Automation=" and "Auto Update State=" and set them both to =0 if they're not already.
See if that fixes it. If not it may be that your installation is corrupted somehow, in which case rename operaprefs.ini to operaprefs.old and see if Opera will then start with a clean default setup.
šŸ™‚