This is a protected Windows system component and has been for a long time. Windows File Protection was vastly improved starting in Vista, which means that it is much harder to mess up than with the old System File Protection in Win2K, Me, and XP.
So that means it is tough to "break" this OCX now. It probably won't even stay unregistrered if you try to. Windows should come along and shovel up the mess you leave like those guys who follow the elephants in a parade.
Sorry about that, I knew better. This library is not supplied by Windows.
What I suspect has occurred, and this isn't a good sign (what the heck are you running on that system?) is that your VB6 design-time licenses are corrupted. In your case this may just have been the result of a silent failure during the installation process. The registry doesn't "just break" contrary to what people may think.
If this is the problem there may be an easy fix, and one that hurts nothing to try anyway. See:
FILE: VB6Cli.exe Fixes License Problems with Visual Basic 6.0