I bought this motherboard few days ago but have major problem. This is my ocnfiguration at this moment:

P4G8x with supplied inf driver installed and usb 2.0 drivers
asus v8460 deluxe graphic card on 43.45 detonator drivers
Sound Blaster Live! Platinum 5.1
External modem
512 Kingstone RAM (2x256) and put in proper slots for dual-channel configuration
Intel Pentium 4 2.4

Nothing is overclocked. Everything runs on factory settings.

The problem is:::

When i want to turn on or restart my PC, it just halts when start booting even before the screen which says how much memory, which processor, ide devices... I just hear long beeps (around 2 sec long) and 2 sec pauses between them. Then i press the reset button and it boots properly. Then i turn off and when i want to turn PC on the same story happens... I set in bios agp mapped memory 128, agp 4x, and primary vga=agp. What could cause this problem. I have 400W power and connected everything by the book. Thanks in advance

Try upping the memory voltage in the bios to 2.6.
This worked for me.

Also make sure you are using the latest BIOS (version 1003).