Sounds like one or more of hte drives is physically failing. When WinXP auto-runs CHKDSK at startup, but the progress-bar stays at zero "forever", that means that it is doing the more-intensive "surface-scan", instead of simply checking the filesystem for consistency. This is triggered by the OS setting one of the filesystem's "fail bits" indicating some sort of physical/device-level problem.
These same sorts of problems can cause then entire OS to freeze, for as much as several minutes at a time, when attempting to access the HD.
I would download the "Western Digital Data Lifeguard" diagnostics bootable floppy (on a different system, possibly), and then boot your system with that to test the drive.
You should probably also do some isolation-testing too, disconnect one of the drives completely from the system (don't forget to set the WD drive to the "single" jumper setting, not "master" - jumper removed, usually), and then use WD DLGDIAG disk to test each one individually.
This will help isolate whether or not both are showing failure symptoms, or just one, even those both may appear to fail if they were connected onto the same shared IDE channel.
Second, spin-up problems at boot, can be caused by bad power or IDE cables/loose connections, drive firmware/hardware issues, or lack of adequate power/poorly-regulated power (failing/under-powered PSU). That's one other reason to test each drive individually, if both test ok singly, then it could be an overall power issue, or a cable issue.
Heat/vibration/abuse are not good things for HDs either, if the HDs aren't kept properly cooled, WD ones have been known to "lose" sectors, and similar system freezes, first intermitten, and then chronic, and then loaded to a crash/Bsod, are aften symptoms of an overheating drive.
OTOH, if the system, after being powered-off and cooled-down for some time, freezes every time, when accessing specific files/directories, then there is likely to be a bad spot on the disk or it is otherwise failing.
IDE HDs spinning back down during bootup, are often due to power or cabling problems, or the HD is failing internal self-tests that it does during booting/spin-up,and shuts down for safety.
Btw, I'm not familiar with 70GB WD IDE HDs, are those 10K RPM Raptors, by any chance? Those need active cooling, for certain. I'm going to assume that they are just standard 80GB IDE HDs, who format out to something like 73GB, I think. My WD 80GB JB drive shows as 74GB physical capacity.
