Thanks to everyone who gave me things to try on this. so far I have run all of them except Tech Tool (cause I don't have it yet) and everything reports as OK.

One thing that was odd was that when I rebooted using a MacOS 9 version of Diskwarrior, it didn't recognise the hard drive, and wanted to initialise it.

I've got three drives partitioned into five drives. one was fine, one has always been too new (? or too big?) for this version of Diskwarrior to see, and one is the boot drive, which Diskwarrior has never had a problem with before now.

Also a temperature check would not check my main HD, but this could be because it doesn't have the right sensors. The other drives checked out OK.

Could this be a sign of a bad connection, or a disk about to fail? The computer still works enough to get by on, but there are lots of freezes and hitches in the finder and in applications.

I don't have Nortons or Virex installed (conflicts with FCP) and I recently did an erase and install of Panther and all my applications.