Random sig[segv|fpe] on 164LX with 256MB RAM

[Andrew Hobgood <chaos strange net>]

Hey all...

Okay... here's the deal.  I'm running RH5.1 on a 21164A 533MHz, with 256MB 
of RAM.  Now, it seems that when my "free" memory (like, really free, not
free buffers) gets below about 10MB (this happens regularly because of the
way Linux allocates cache)... things start to almost randomly segfault and
sigfpe.  Now, this usually isn't TOO big of a problem (I've written a quick
script to wrap around some smaller programs, like mpg123, etc. to intercept
and ignore the FPE's and SEGV's), but sometimes things like, oh, rxvt 
decide to thrash themselves, then my X server croaks.

It's starting to get *really* annoying, and I'm wondering if anyone knows
of:

A) A program that will let me check my memory for errors to see what's going
   on (ala memtest86, but for the Alpha)
B) Any sorts of fixes for this kind of stuff (compile flags?  kernel patches?
   hardware fixes?  Pagan sacrifices of virgin Intel users?) that will
   keep it from happening?

Well, thanks in advance...

/Andrew