Here are some suggestions off the top:
1. Check the interface (ribbon) cable. While common sense says that, if one drive works off the cable, both should, this is not necessarily so. Not likely the problem, but an easy place to start.
2. Check your drive jumpers on both HDDs. You likely know that your slave should be jumpered for slave. Also, the master sometimes has different jumper settings for single and master.
3. Although, as you said, CMOS recognizes your HDD at the proper size, be sure it lists the heads, cylinders, sectors, landing zone, and write precompensation correctly.
4. Recheck the partition. Boot from your Windows Startup disk and run FDISK /STATUS to make sure it recognizes the partition.
5. Try another known good HDD with your master if one is available. Although it is rare, you might just have a bad HDD.
I'm not sure you'll find the answer here, but these are the fundamental first steps. Butch
"It's what you learn after you know it all that counts"