Was your computer running OK? Were you getting error messages or BSOD's? If not, I strongly urge you not to use a registry cleaner unless you are well versed in the registry and know exactly what you are doing.
Windows is a closed source system. Developers of registry cleaners do not have the core code of Win 7 and are not working on definitive information, but rather they are going on past knowledge and experience. Automatic cleaners will usually have to do some guesswork.
Modifying registry keys incorrectly can cause Windows instability, or make Windows unbootable. No registry cleaner is completely safe and the potential is ever present to cause more problems than they claim to fix.
Registry cleaners cannot distinguish between good and bad. If you run a registry cleaner, it will delete all those keys which are obsolete and sitting idle; but in reality, those keys may well be needed by some programs or windows at a later time.
Win 7 is much more efficient at managing the registry than previous Windows versions. If you are very knowledgeable of the registry, you can use Ccleaner to delete keys left over when uninstalling programs. However, these few keys will not make 1 millisecond's difference in performance. If you run Ccleaner or any other registry cleaner and do not know precisely what you are doing, you will have problems down the road. There are no gains to be had from using a registry cleaner and the risk is great.
Forget all the "wisdom" you learned about XP. Win 7 is not XP and does not manage the registry the same as XP.
Are registry cleaners necessary?
Back up the registry
Anyways, I have a family member who goes to a university. They use Symantec Endpoint Protection there. I got it installed once before, a while back but the LiveUpdate portion of it got corrupted and I was unable to use it. With that being said, when I try to install it now, it rolls back during installation. If I wipe my drive, and reinstall a fresh Windows 7 OS on it and try SEP again, does anyone think that would solve the problem?
Yes it most likely would. I suggest using Symantec's uninstaller first and try to remove all of the program that way; then reinstall it.