[AccessD] Out of Memory problems - AXP/WinXP

I'm wracking my brains to figure out why an AXP application of ours
exhibits different behavior on different but similar machines.  We have
an app that simply sits there and distributes reports, either by email,
to a printer or to PDF files.  It operates on a timer and checks to see
if new data has been received.  If it has, it checks the distributions
configured and sends the reports.  The baffling thing is that at some
point, we get a "not enough memory" error that brings it to a halt.  The
brute force method is to shut the thing down and restart it.  We could
even do that automatically, but the trouble is we can't figure out what
causes it.  It does not appear to be memory leak and we've tried
everything we can think of: tweaking the virtual memory, turning off
file indexing, changing the interval, updating the jet service pack to
8, etc.  It is very consistent on each machine, but the machines we can
test it on don't fall over at the same point.   The best performance
comes from the machine with the least RAM, the oldest video card and the
slowest processor, but all are running WinXP SP-1 and OXP SP-2.  All the
machines are P-4s, have 40GB HD and have some flavor of NVIDIA Getforce2
adapters.  The best performance is coming from the 256 MB RAM machine
with a 1.50 Ghz CPU.

I'm tearing my hair out in handfuls, and I can't find a clue anywhere
I've looked.  Can anyone shed any light on this?

Charlotte Foust