Greetings, I've recently built a Pentium III 700Mhz PC for classic gaming, it's very simular to the system I had back in the day, same modle of motherboard, etc. I fresh installed Windows 98SE, so this problem im about to explain is not any "garbage" on the system such as viruses, trojans, malware, or spyware. Anyways, i've got a real stinker of a problem, everytime I plug-in a CAT5 cable into my NIC [aka everytime that PC has internet access], the AGP port suffers with random stuttering, online games such as Quake 3, online mutiplayer Deus Ex, etc absolutly are impossible to play online, it stutters about every second and the random stutter is pretty bad in the offline story mode too [random pauses for 3-5seconds at a time, or sometimes "jitters" it's NOT framerate drop, other wise perfect framerates]. The sound also will start to stutter severly anytime the AGP port stutters, if and ONLY when the PC is connected to the internet... like the very second the CAT5 is inserted into the NIC. As soon as I unplug to remove that PC from the internet, everything goes to normal and the AGP card flies through most games. I've tried different brands of NICs and the same issue. I even tried WiFi, inserting a WiFi adapter solved half the issue... the sound no longer stutters when the AGP stutters. However it did NOT remedy the AGP stutter when the PC has internet access. I also tried a 500watt PSU to see if maybe the 350watt PSU it normally has was running out of juice, but it's not the 350watt is is perfectly fine. The full system specs of that PC are; Windows 98SE, 700Mhz Pentium III Coppermine, ASUS P3B-F v1.04 Motherboard, 512 MB RAM, 17" CRT monitor, GeForce FX 5500 256MB AGP, D-Link DFE530-TX+ PCI ethernet card, SB16 SCSI + NEC XR385 [DB60XG clone], 13GB Hard Drive, 3.5" Floppy Drive, Internal 100MB ZIP Drive. Once again, the AGP stutters everytime the CAT5 is plugged in and the PC is connected to the internet. Any and all help to get this resolved is much appreciated. Thanks in advance!