The "cab files are missing or corrupt" error message when attempting to install a downloaded application is usually a sign that it didn't download properly, maybe got corrupted somewhere between the source and your PC. That would be even more plausible if other applications you've recently downloaded have installed okay, making it unlikely that the problem is at your end. Delete that download package and try downloading it again.
I cannot stress too much the importance of avoiding the use of so-called 'Registry Cleaners', especially free ones. However, in this case I assume you downloaded the trial version. This has only limited functions, which probably means it can find registry errors but won't correct them. You have to buy it for that to work. That's why the same 'errors' keep comimg up, but they may not be errors at all, simply a 'scam' to get money out of you. Then if you do buy it, it might remove entries which are vital for windows to run properly. But by then it's too late, they have your money and you won't get it back. Stay away from them.
Without seeing the actual registry-errors it claims to have found it's impossible to make any connection between them and your nero problem, but I'm leaning towards the opinion that there's no connection. If the problem was getting nero to run after it installed successfully, I would have said it could be the registry errors, but that's not the case here. Definitely sounds like you have a bad download so just try downloading it again, from a different website if possible. It may only be a trial version of course if you get it from another website, but even that will do just to test if it will install. If it still won't install, we'll try to help you further.
To happyrck -- the OP has already taken the matter up with nero support (read the post) but it has a 2-week response time apparently. hardly surprising therefore that he/she has come to us. I wouldn't say nero support was the "best bet" in those circumstances!
Edited by pip22, 23 February 2008 - 07:14 PM.