Looking at the System Mechanic's page, I'm wondering if they're not over promising their capabilities. A lot of the stuff they do can easily be done with free software, as has been noted, but a few items I've not seen effectively implemented in the past, though I'm willing to admit System Mechanic may have it right. For most of what you want to do, something like CCleaner from Priform would work well as it gives you the ability to do most of the standard cleanup tasks that the disk cleanup utility does, plus a bunch of extras that it doesn't, including cleaning up after programs that leave their garbage files lying around.
Also, while not as much of a concern as it used to be, sometimes cleaning the registry can be helpful, which it sounds like here. Try CCleaner's registry cleanup utility, as that may solve your problem with the missing file, and if you're worried about losing anything, you have the option of backing up the registry items before they get changed.
1What problems is it finding exactly? You shouldn't try to fix registry problems on a system that works, because a stable system's registry, won't be changed all that often. – Ramhound – 2013-05-17T13:29:13.917
@Ramhound I want to disable a sartup that can't find a file that appears to be useless. That computer had ransomware that we had to remove and I installed system mechanic to clean the computer further. Now we got rid of the ransomware and the only problem that appears to be left i that upon startup, the computer displays an error message in windows (Vista) that it can't find some Progra~\v54.dat or similar (I'm not sitting at that computer right now, I closed it as working since it is good just ignoring the error message). – Niklas – 2013-05-17T15:35:25.807
1There are free tools that exists. Why would you purchase a paid product? Sounds like you didn't remove everything from the registry. – Ramhound – 2013-05-17T15:48:50.503
@Ramhound You're right, I need to clean something from the registry that calls that startup to look for the .dat file. But I can't find which startup program that does it. It's like a rotten link. – Niklas – 2013-05-17T16:37:47.643
System Mechanic isn't the tool you should use because there are better free solutions. – Ramhound – 2013-05-17T17:14:04.360
Autoruns would probably enable you to find it but these things load multiple exploits. The only safe thing to do is to reinstall Windows. – David Marshall – 2013-05-17T17:33:15.210