Monitor won't pickup after sleeping

After computer sleeps, sometimes (only built this computer 2 days ago) my monitor won't wake up. My case fans are running, keyboard light is on, but nothing happens. Sometimes no DVI signal popups. After shutting off, messing with the cords for the monitor, turn on, it will POST, then windows logging in, I click my account (only user on my computer, and it says Locked for some reason) and it goes black, I reset computer and everythings fine.

Besides this, I have no problems. My CPU temps idle around 35. I didn't OC. I can run games fine (wc3/crysis/hon/cs). Highest I've seen my temp go is 55 during crysis on max settings.

# Motherboard P7P55D ASUS
# CPU i7 750 stock
# Video card XFX Radeon 4890
# RAM : 2x 2gb OCZ gold 12800
# Power supply: OCZ Stealth X stream 700w
# Monitor ASUS 24" VH22