Unexpected IRQ trap

Hello, i have recently set an old P120 of mine as a samba server, with an AMI Raid card and a Kingston KNE120 TX network card. This all works okay, except when I try to copy a large amount of files to or from the server, i get an "kernel : unexpected IRQ trap at vector 5f", and the machine loses network connectivity and has to be rebooted. I'd like to sort this out, but i have no idea where to start, as the usual sources seem to have very little info! Thanks, Iain