Cold Boot? Fat Chance!

[GiganticDays]

Athlon XP2400
ASRock K7VM2 Motherboard (Rev 2.02)
Seagate 80Gb HDD
512Mb PC266 RAM
Windows XP Home

The above system is exhibiting a strange problem ie. if trying to boot from cold (say after being switched off for a few hours) the BIOS cannot detect the HDD and will not boot. Once it's been switched on for a while it boots up ok. All I've tried so far is swapping the data cable, but it's a frustrating problem to diagnose as once I've tried a couple of things, the PC has warmed up sufficiently to work normally so I have to let it stand for a few hours before starting again.
Can anyone suggest anything?

[TOAD6147]

Did you run setup in the BIOS so the hdd can be properly detected? Also, is the power supply healthy and of sufficient output to run that Athlon? Also, since the problem seems to go away when the unit is warm try a hdd diagnostic utility called SeaTools.

[GiganticDays]

Sorry, should have said; tried Seatools and the drive passes. Have also run the BIOS setup. Can't speak for the health of the PSU but I've built many systems more demanding using this model. I'll try swapping the PSU next.

[Bill in SD, CA]

Have you checked the CMOS battery?

Bill