I have been experimenting with several different registry cleaners over the years. Found some good ones, and some so so ones. The thing I never saw was one that could clean the empty entries in your registry.
So I down loaded the trial version to see if there was really that many empty entries on my pc. There were almost 900. So I thought this might be worth looking into. So I did some research and found both good and bad about this product. But deleting 900 worthless entries seemed appealing because that's 900 less the pc has to sort through.
So I went ahead and bought the program. After I did an install, and before the clean, I made a restore point just in case. So I cleaned the registry. Things were much faster. But I also found that some programs quit working.
I use movie maker a lot, so that was the first. So I did an xp repair install and that fixed it. The next was yahoo messenger. Anyway, I have a bunch of programs I do not use very often, so I don't know how it has affected them. But I would not reccomend using this program. It's called: RegCure.
Unless you are computer savvy, and know how to deal with such stuff and have the time to do it. I don't suggest it. I can fix all stuff messed up by reinstalling them as I find them. But I thought I would post this warning.