It is really difficult to troubleshoot the problem you're describing without a tech spending a lot of time on your system. It could be that Windows is having problems or your hard drive might be experiencing issues. I don't use registry scanners/fixers. I think they are dangerous. Nobody is going to know enough about every single registry entry to know whether or not it's safe to "fix." The alternative is to blindly trust the registry scanner and I'm not comfortable with that either.
Sometimes computer manufacturer's will include utilities to check system health. If you have access to those, I would try running those first.Bad hardware drivers can also cause problems, so if you've recently installed any hardware, you might want to check for updated drivers. To check your hard disk, try running the Windows utility, chkdsk, to see if it finds any bad blocks. Also, if you can determine who makes your particular hard drive, you can usually download software from the manufacturer's website to check the fitness of your hard disk more thoroughly. If none of these things resolve your problem, I would reload the computer with system restore discs.
I know, I know it's been asked a million times but I didn't see anything that applies to me. My hang up could be 2 mins after I power up or 2 hours later. Sometimes it is so bad I have to pull the A/C and then the battery pack. I have run registry scans and , depending on which one I run, I have thousands of problems or nothing serious. When the problem first started, 3-4 weeks ago, it was only when I was using IE and taking surveys. Now it may fail while I am still in the desktop or using a program not related to IE. I have deleted all temp files and cookies and set up to clear both at shutdown. I have asked for help on several sites and so far no one has even bothered to respond. So, here I am at CNET. Let's see if this is any different.