Server "freezing"

[Rob Brandt]

I am having a problem for the last month or so and don't know what to 
do about it.  It's happened 4 times in November, and last night as 
well.

The server "freezes".  It is completely unresponsive to the keyboard, 
http, mail services, telnet, ssh, and ftp.  I can successfully ping 
it.

When this has happened, I end up having to shut it down at the power 
button and reboot.  When rebooting it goes through the filesystem 
check and often encounters and Unexpected Inconsistency, requiring me 
to run fsck.  After going through that, it fixes several things 
(sometimes a lot, sometimes a little) and then loads properly and all 
is well.  For a while.  Then it does it again in 2 to 14 days.  I 
don't know whether the unexpected inconsistency is the cause or the 
result of the "freeze".

Are there any diagnostics that I can perform to discover the problem? 
If there are file system errors causing this, are there utilities 
that can be run that will prevent it or minimize the risk?

Any advice appreciated.  Running:

Beige G3 Tower;
YDL 2.2
768 MB Ram
YDL boot disk : original 4gig IDE (hda8)
Data disk for /home and /var: New (2 mos) 60 gig IBM (hdb2 & 3)

All of the above partitions have exhibited the Unexpected Inconsistency.

Rob