When i used the register tool from CCleaner it said that there were a lot of errors with the windows updates... I didnt trust it and made a backup. After that i clicked FIX. The next day I wanted to uninstall a program, but I saw that almost all the updates were gone from the list: in dutch they're named: XP beveilingingsupdate, I think its XP securityupdate in english...

the Hotfix or update is the old ones it for if new one is no good so you can go if no good so it ok to clean out as you dont need one one year I got 80 if you need to take one you get told to take new fist & go back. one keep for a week or 2 or 3 dont need take out so you OK.

Untick the hotfix uninstallers tick box in the cleaners advanced section. It hasn't removed the hotfixes themselves, just the uninstallers (meaning if you needed to uninstall a hotfix because of a problem you couldn't). Generally a good idea not to tick anything in the advanced section unless you know what you're doing.

When can one feel safe to remove the hotfix uninstallers? I show over 600meg being used on this system.

That's entirely your choice. If Windows has been problem free for 2-3 weeks after a Windows update they should be safe to remove, but there are risks involved in deleting them (ie if a hotfix causes a problem and needs removing), that's why they are in the advanced section.