IDS 7.31 hangs during checkpoint

I'm using IDS 7.31 TC2 on Windows NT 4.0 Sp3. I've got a somewhat consistent hang every 5-7 days on my database server during a checkpoint. onstat -p says the status is blocked on the checkpoint, but everything else looks good. Usually I do an onmode -u/onmode -m to restart and everything goes back to it's merry way. Could this be something to do with some database resource not being large enough? Or is this an Informix bug where they don't handle their critical sections right in the checkpoint code? I've sent in a bunch of stuff to Informix tech support with no meaningful response. Cheers