I just had a strange thing happen. My XP box (Dual Xeon 3.2GHz HT/2GB/Dell Perc RAID5) just got pokey. Process Explorer showed Hardware Interrups taking 20% of the CPU. After four or five minutes, it went away and now bounces between 0 and 1.5%.

Where do I begin troubleshooting this, other than madly unplugging things if it happens again? I did unplug my card reader, to no effect. The machine doubles as a file server for two other people (hence the RAID), but I never even notice their activity in normal use.

Thoughts? Thanks.

-Zeke