I believe Wazz is correct. The best thing you could do would be to uninstall opera and then reinstall it. If that doesn't work, then perhaps you have a corrupt download and need to redownload it and try again.
When I downloaded opera, it went very smooth and I didn't have any problems with it.(although Idon't use it and removed it.....it worked fine until then.)
Please let us know the results, and cure to your problem, when you find it.