What have you done to clean up the machine? Take off the computer cover and use compressed air to blow all the dust and junk from inside.. Next, follow the steps in the links below to eliminate unnecessary start up files and services and delete all the junk files from the computer:
Cleanup Steps To Do
Just in case it's simply the monitor going bad, try swapping in a known "good" monitor and see if the problem still occurs.
Hope this helps and let us know more.
I have a Dell Inspiron 4100 about 5 years old. I use Windows XP Home.
For a few months now, while I'm on the computer, the screen freezes for a while, goes black and after a short while, it "unfreezes" and comes back on. On some occasions, I have to manually shut down because Ctl. Alt Delete doesn't work.
Does anyone have an answer?