I'm running XP Home updated to latest release online
Unfortunately in a DELL DIMENSION 3100, with two SATA drives installed, formatted and working however drive 2 a SAMSUNG HD250HJ is very often not picked up by XP including in my computer and device manager.
It powers up every time and is picked up by the BIOS and a drive scan comes back fine in start up prior to windows kciking in.
Changed the leads, changed SATA ports and my Western Digital Drive is picked up fine on both so I know it is not down to the motherboard or sockets. The WD drive is only 40GB though.
No jumper settings as they are SATA drives
Royal pain in the bum if anyone can help

Had this problem for a long time until I figured out that the cables were not staying securely plugged into the SATA ports on the board, causing intermitent connection loss. I tossed the cheap "stiff" cables that came with the drives and used the softer, more pliable cables that came with my motherboard, solved my drive disappearing problem anyhow.

just for laughs...
Is your drive formated as a basic or dynamic??
I have a sata drive I use in an external hub and I formatted it as dynamic..
stupid me..
anyhow.. each time I use this drive, to pull something off it, etc.. I have to go into my 'computer management', then goto 'storage', then I finally goto my 'drive management' section.. I then must right click on the drive in question, and choose the option to re-activate the drive.....
If your bios see's your drive, but windows doesn't, make sure the drive is activated..

Hope that helps... If not, then I dunno.. I'm sure some savvy tech here might be able to figure it out 4 ya....

If only either of those options would help - changed cables (no change)
Drive simply does not appear in windows anywhere at all

have you tried to look for drive from a prompt boot or safe boot? try that and then u can get data off it... sounds like it may be haeding south... or maybe in a conflicting format to boot drive...

Still no joy but appreciate the idea. Last ditch effort today will be install a new hard drive and see if its detected, stick the current one in a caddie and try usb connection and if that fails the whole things going out the bedroom window. Will let you all know

Well boys and girls new hard drive installed and not detected by windows just BIOS, sooooo non detected hard drive removed put in a caddy and plugged in USB style. Works a treat which would suggest DELL's fantastic motherboard is going in the bin.