First, don't pay for the reg cleaner, there are plenty of free products around.CCleaner (click here), Eusing Registry Cleaner click here
plenty of others.
Registry fixers are not the first thing to try when your PC regularly locks up, something more serious is usually the cause.
The memory `advice` is so general as to be useless.
How long has your machine been playing up, what antivirus software do you use, what firewall, does the machine crash from cold, or when it's been on for a while?
Try a system file check; click here