Anybody had this happen? When the "No Signal" appears on the monitor and the monitor goes to sleep, the computer stays on but does nothing. I looked up the causes and cures on Youtube. Thought it would be the worst case, needing new graphic card. But I went through all the simple checks first. Cables, power supply voltages, clean out the dust from the fans and circuit boards using cotton swabs and auto MAF spray. Computer still didn't work. Went back in and pulled the RAM boards out, cleaned the terminals and stuck them back in. Turned on the computer and it now works. Whew, what a relief. I would have lost a lot of apps if I had to buy a new computer. This one is only 4 years old. Just thought I would mention it here so others will know about it.