I'll explain this from the beginning the best i can. I took my box apart to clean out the dust around the processor and the rest of the board. Before i went into the box i grounded myself so no static electricity would harm anything inside. I took a vacuum and sucked up most of the dust. The vacuum did not touch the motherboard or any other componet except the heat sink at any time. When i put everything back together and booted up, everything worked fine. Later on during the day i shut the computer down to remove the Cat5 cable going into the NIC and plugged in a new one. When i rebooted there was no display on the screen. The only display on the monitor was a little box that i always get when i shut the computer down telling me that my monitor is working correctly. The power LED button on my box is always green, but this time it is orange. After that it was pretty late so i went to bed. When i woke up the next morning everything worked fine. I had the computer running all day with no problem. When i came back later that night from getting wings with a friend the monitor is frozen with the screen saver it was running. Nothing would work, so i shut down the unit and tried to reboot and got the same error as last time, no monitor display and a orange LED light on the power button on my box. Again i went to bed woke up and booted up and again it works fine. What's going on? Does anyone have a clue. I'm thinking maybe my video card is going bad. I'm running Slack 9.1 and my video card is the Nvidia Geforce2 Ultra. I've had this computer for a couple of years now and never ran into this kind of problem before. Sorry this is so long, but i'm trying to give you guys as much info as i can. Thanks.

I've had this prolem before, and there may several causes. Just try pulling your video card the WHOLE way out of the slot, and then putting it back in, pushing it in till it won't go any farther. That fixed it for me.
Noah

Using a vacuum cleaner near the motherboard and other parts of the system is very dangerous. A vacuum cleaner creates alot of ions and these ions creates static electricity. Thats why special vacuum cleaners that are design for electronic components have ways to shunt the static electricity to ground. Next time, try using compressed air to remove the dust.

After you did what njbrain told you, disconnect all power cables in the system and reconnect them. Sometimes this may be the problem when you are messing around in the computer.

My guess would be your power supply is about to give up the ghost. If it were the video card you'd get a beep code, usually 1 long and 2 short.