random system crashes

Hello all!

I have a big problem with one of my webservers which is running TUX. I don't 
know if TUX is the reason for that but the system crashes from time to time 
and there is nothing special with it except the TUX.
The crashes are a little uncommon: The system reacts on nothing but ping. Even 
the local console isn't responding but the ping-timing is low as under usual 
operation. There is nothing in the logfiles that points to a problem. They 
just stop and the next messages I see are the bootup messages of the kernel 
(after reboot). One time I just had top running on the machine as it crashed 
and I saw nothing special: Enough free memory, no high load and over 50% idle 
time on the two CPUs, etc.. And from one moment to the other it was frozen.
I just thought someone could have similar problems and have a solution. The 
hardware was completely replaced by the hoster but the problem persists. Just 
the HD stayed the same but the RAID-Controller reported no failures. So I 
think it's not a hardware problem.

The system is a dual P3 with 1.266 GHz, 1GB ECC-SDRAM from IBM (x330) with a 
SCSI RAID-Controller and 2x36GB IBM SCSI disks.

The kernel Version is 2.4.18 with TUX 2.2.7. I don't know if there's any other 
patch in the kernel. I have Apache as "backend" server.

Thanks in advance!

Marco.