After finding over 10,000 registry entries for Kontakt that needed to be removed due to a bad install/uninstall, I needed a registry editor that would find and delete them for me, as there was no way to manually remove that many without spending the rest of my life doing so. I found several online but most wanted money before deleting or they would only delete one at a time (I can do that with regedit) or they had no way of deleting them at all. Then I discovered RegSeeker which did the job for free, tho you can donate to the cause.
 
Are there any better ones out there?

While its not a reg editor ccleaner will scan the registry and report broken entries and if you elect to remove them. It may not solve the issue but it may reduce the amount of manual editing.

I have used it for years and its never caused me a problem.

CCleaner here as well

CCleaner here as well

CCleaner here also.

I use to make good money fixing people's systems after they used CCleaner.
Could be that they already had issues that they were desperately trying to fix - but on the other hand when you find a gun in the end user's hands and he's already shot off both his feet it doesn't take a lot of imagination to guess some of what happened.** 
Now that I'm more corporate service oriented I don't see it as much, hopefully it's gotten better.
 
**side note
I learned early on never to bad mouth the previous tech.
People would often say the previous tech tried to install this or fix that - the previous tech often turned out to be either themselves, a close relative (such as husband), coworker, friend or even their boss.  
 

I also use ccleaner and it works for most issues, but not for this one.
 
I'm still wrapping my head around why there was over 10K entries for one program.