That could be the culprit...I have an active SCSI bus with an external hard drive and a CD-ROM.

I probably didn't notice this before because:

1. My hearing is steadily going.

2. I usually listen to music while I compute.

3. I often have my space heater on, plus I live in a basement so there are a lot of heaters/fans/pipes making noises at any given time.

I'll try a floppy-only boot when I get home.