The whole issue of Registry Cleaners is controversial. ‘RegSeeker’ is one such tool. On whether it’s safe, i will quote an expert who’s opinion i trust [from a techsupportalert.com forum entry entitled “WinUtilities 9 Free“]:
Another good one is RegSeeker. You can comfortably wipe out a whole OS with this one without even trying. Not quite as effective as Darik’s Boot, but you get the picture
This is their slogan:
“RegSeeker is a perfect companion for your Windows registry”
What they don’t say is that after using it you likely won’t have any registry left for it to be friends with
RegSeeker might have its uses, but its danger outweighs its usefulness for all but expert users.