|You say it tells you the "C: drive is full and it's not possible". How much space is left when you get that message?|
It's acting like a swap file--it gets bigger the longer the computer is on and deletes itself when you shut down the computer. But a swap file taking up 125 gig is hard to imagine. You're sure it's 125 gig and not 12.5 gig or even 125 meg?
How large is the C: drive partition?
How much ram do you have?