The clue is in your own comment that your computer is running fine. How can that be if this software has found over 4500 critical problems?
This is a common ploy by such registry cleaning software developers. Tell the victim, err... customer, that there are thousands of critical errors and the computer is likely to blow up, then when the customer attempts to fix the problems, demand money to purchase the full program to clear the errors.
I will be honest, there may well be that many unused entries in the registry. But the registry holds hundreds of thousands of entries and is, after all that, just a simple database. In databases, if an entry is unused it just sits there doing nothing. It doesn't affect how the registry runs and it doesn't affect the performance of the system.
If there were any bad errors in your systems registry then at the very least some affected programs would fail or the whole system would fail completely.
So, I would suggest you stay away from any "fixes".