Laptop monitor occasionally craps out and won't respond

Dell e1505 runs XP MCE.

2 scenarios

1) PC is on and running. I walk away for a while or whatever and when I come back the screen won't wake back up.

2) PC is running with power cord plugged in. I unplug and screen goes black and won't respond/wake up.

In both scenarios the PC stays on and I am forced to shut down by pressing and holding the power button which I know is generally a no-no.

lastly this doesn't happen all the time. Sometimes I walk away come back and teh monitor responds fine and sometimes I unplug the power cord from the back of the laptop and monitor stays on just fine.

Dell support thought I needed to install video card driver update. Gave the support guy remote access and he messed around for like an hour and then said he updated the drivers and if it continues happening I need to send the laptop in.

Well its still happening and sending it in seems a bit extreme so any help would be much appreciated.

this could also be a problem with waking from the sleep state, where the OS and bios need to work hand in hand to wake the system from sleep state. I have seen system with unstable bios having this issue. I would recoment bios upgrade if there is any available.