:lame :p Its AGP 8x
It looks to me like a CPU/Motherboard issue. Your P4 has a FSB running at 400MHz, which means your board is also running at that speed. Which also means your memory may only be running at 266MHz. What is the brand and model of your RAM?
The video card is not that great, but its ok. The gpu clock speed is about 300MHz and the memory clock speed is about 350MHz. On the plus side, it can be overclocked to 700MHz. Don't know how, but from what I have read, it can be done.
The fact that you are having problems on certain maps tells me that your system is having issues “processing” those maps. That points to the CPU, motherboard and video card.
I'm sure you NIC is fine.