So you did not head my advice and ran a registry cleaner or you are thinking of running a registry cleaner.
What should you do first?
Well you should backup your registry.
This can be done in 2 ways.
The first way is to create a system restore point details of which can be found at System Restore Frequently Asked Questions.
Then if your system becomes unstable you can then hopefully restore your system to a time when it worked.
The second method is to go to Start , Run and then type regedit
You can then export a copy of the registry to a flash drive or other media so that if the worst happens and your computer becomes unstable then you are able to restore a copy of the registry from the backup that you made.