Could not find the environment option entered

I am having alot of problems with my pc. It all began with my roxio cd burning program stopped working. Next microsoft word,excel, etc stopped working. Everything gives me this error, "The system could not find the environment option entered". Now when I try to run anything it gives me that error. If i download something to search for malware etc when I go to install the program it gives me the environment error. I am running as an administrator and nothing works at the cmd prompt. I have tried system restore, only to be let down by either no change in my system or system restore not being able to restore to the point that I want it restored. I have tried the system repair via vista disk with no results. Also, when I open properties on my computer it does not recognize my processor nor how much ram I have installed. And nmy computer is ridiculously SLOW!!!

I am pondering reinstalling the os. I have backed up everything I want and got my key for my current os, which is preinstalled. Please either help me with my current situation or guide me through a reinstallation process.