Hard lockups on E250

[Roderick van Domburg]

Hello there,

For about a month now I've been experiencing high instability on my E250 
  (UP): it just locks up hard. It does so after either a couple of hours 
or a day or so, depending on the system load. No messages given 
whatsoever, it just sits there at the console waiting for me to reset it.

The system normally runs a fairly high-volume Apache2 webserver. When 
Apache is running, the system doesn't survive for much longer than an 
hour. When I shut everything down however, leaving the system bare-boned 
so to speak, it'll run for about a day.

Like I said, it hasn't always done this at all. It's been like this for 
a month or so and recent cvsup'ing hasn't resolved it so far.

Anyone else experiencing this? Any ideas?

Regards,

Roderick