This is NOT a sign of bad memory. GEOS cannot run on more than 32MB of RAM.
The memory allocation system cannot deal with more than 32MB because it
allocates a table to keep track of the memory. If the memory is too large the
table will wrap around on itself and die. I believe there is a fix to this in
the NewDeal version of GEOS, but don't quote me on that.
The solution is to run GEOS under Windows where you can specify the amount
of memory to let GEOS think it has (set it to 4 or 8MB, won't need more than
that).
Nathan