Went to bed with working computer, woke up with the opposite

[thedon01]

last night i shut my desktop down and this morning when i started the computer i had serious issues.

Issue 1 (non network related):
My computer was not loading, it wouldn't even load into the bios. i began disconnecting all devices (external HDD, keyboard, etc), still didn't solve the problem. I later solved the issue by tinkering with the RAM sticks. Computer now loads into windows xp.


Issue 2 (network related).
Since this morning i haven't been able to connect this pc to the internet. Originally this pc is hardwired to my router (linksys WRT54G) and i'm using a Scientific Atlanta DPC2100 modem from Time Warner. I'm sending packets, but not receiving, thus getting a limited to no connectivity error.

Things i've done that have resulted in the same problem:
1. Connected the problematic pc via Ethernet (on board) to the modem/router.
2. Installed a pci network card and drivers and tried to connect to modem/router.
3. connected pc to modem via usb.
4. uninstalled and reinstalled the drivers for the modem, for the on board network card, and the pci network card.
5. Performed a System Restore to a week ago.
6. Plugged cords into different outlets
7. Tried different Ethernet and USB cables

Things i've done that have had success:
1. Connected a 2nd pc to modem via Ethernet and was able to access the internet.
2. Connected a 2nd pc to the router via Ethernet and was able to access the internet.

Problematic PC Specs:
Pentium 4 3.0GHZ
160GB RAM
3.0GB RAM
Windows XP SP3

thank for taking the time to help, i really need it.