Ok, I've got a crazy file server put together here - it's a Syntax socket A mobo w/ a Athlon 1800+ in it. The onboard IDE ports go to a 40gig C drive and a dvd burner. Then I've got a Promise Ultra 100 TX2 IDE RAID card (with a pair of 80gigs and a 200gig from it) plus a something-or-other Silicon Image based IDE card w/ 2 more hard drives on it.

Of all those drives, one of the 80s on the promise is its own drive letter, used as the temp storage for bittorrent downloads (dl'ing old tv shows mostly), called E:. All the rest are joined w/ WinXP's drive management in a big honkin' 500+ gig spanned drive for storage for my HTPC (ripped dvd collection, plus some overflow recorded tv), called Z:.

Now, the computer's been flaky for a few days, randomly rebooting spontaneously. Over the weekend I was gone and came back to it locked up. A reboot, and a check of the system logs... showed lots of read and write errors to various discs, but only to the 3 attached to the promise controller. Amongst rebooting several times the E and/or Z drives would disappear within a few minutes of bootup (but they always were both there on boot, and the promise controller always found all three discs in its boot sequence just fine).

I highly doubt 3 discs would be failing at the same time (and no others, which I'd see if there wsa a power surge or something) so I'm suspecting the Promise controller. I'm thinking about buying a replacement TX2 on ebay (can get it for ~15 shipped as opposed to 75 on newegg!) and just swap it in.

Is there anything else I should test first? If I do that, connecting the drives the same, windows shouldn't even know anything happened, right? So my spanned drive should be still there just fine?

Theoretically yes, so long as Windows has built-in drivers for whatever else you're trying. If it doesn't, it will break the span upon startup (though you could always build it again).

I would suggest making a backup of your Windows C: drive, that way if something goes wrong you can go back to the original hardware config, restore from the backup and have your "drive" back.

Well, I ordered a replacement TX2 on ebay and am waiting for it to arrive. It should just plug in and be like it was before... although I know they have different firmwares out there, and the older ones don't support large drives. If it's an older firmware I'll have to flash that and THEN I'll be set