Codec error upon startup

I think all is fine, except for this annoying alert

Your virus scanner might have deleted that file. It is obviously a false positive.

You can fix it by running the K-Lite installer again. You can simply upgrade, no need to uninstall first.

Um ok, btw it happened because of reinstalling/intalling and then system restore, quite messy really

System restore does not fully reset your computer to a previous state. It ignores certain file types and only restores specific parts of the system. It can break programs. You should only use it in case a major problems. It should not be use to uninstall programs or revert to previous versions of programs. Always try that first by using the installer/uninstaller of the application itself.