They are all real, however, what you think of as an error and what they think of as an error are different.
You are probably thinking of something like a partial corruption, deleted system critical keys etc.
What they think of as an error are keys that point to files that don't exist (i.e. you unistalled the program but forgot that one entry) They consider empyt keys errors (like considering an empty folder a waste therefore it should be deletedx.) File types that aren't in use. You removed a program that used the .something and they registered but didn't unregister. There are a variety of other things some of them more like what you'd consider a real error but if your system is running fine its not a problem.
If you do run one of these programs, what it will do is remove this and reduce the size of your registry (c:\windows\system32\config\system and systems is actually the file name not a folder) and you system will boot and run a little faster. But you don't need to pay for that, consult google for a free one.
