The same thing is happening to me on an almost equal pc Intel Pentium 4 2.53GHz, 768 MB de RAM, no video card.
It happened before with jaunty and now it's happening with karmic, both 32bit server editions), I removed the video card, that was causing problems (I couldn't even install any linux with that video card) and it worked perfectly, but after 10 minutes or so every network service just freezes (ssh, apache, ftp) though it still have internet access.
The server pc and router are far from my desktop pc, and for several reasons I can't move the router from where it is, so I would have to buy more lan cable. Thus I can't have both pcs connected and use both at the same time.
At first, I thought the server was just freezing, but I think it's not the case, because I used the server pc (swapping it with my desktop one a couple of times) and it works just fine, I have used it for a couple of hours without problems. But since I can't look at both pcs at the same time, I cannot assure it's not actually freezing.
If I reboot the server, it works for another 10 minutes or so. And sometimes, if the stars are right, it may say up and running for a day or two. But that's it's maximum of tolerance...
Then I thought it might be the router, because once happened that I restarted the router and it worked, but it was probably just by chance...
I tried with the logs and this is all I got:
[ 5.387507] [drm] DAC-5: set mode 640x480 0
[ 5.807320] [drm:drm_helper_initial_config] *ERROR* connectors have no modes,
using standard modes
[ 5.822621] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0
[ 5.875746] lp0: using parport0 (interrupt-driven).
[ 6.021448] Intel ICH 0000:00:1f.5: PCI INT B -> GSI 17 (level, low) -> IRQ 1
7
[ 6.021499] Intel ICH 0000:00:1f.5: setting latency timer to 64
[ 6.042993] eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
[ 6.344038] intel8x0_measure_ac97_clock: measured 53746 usecs (2590 samples)
[ 6.344044] intel8x0: clocking to 48000
[ 16.248015] eth0: no IPv6 routers present
Could it be the lan card? I have a spare (good) one, so I have to try.
I'm completely lost here, and I could really use a hand.
Thanks!