Ay up owd cocker, now there's nowt wrong with having an Athlon Processor, I say this because I'm still using my 1.3 GHz Palomino (running Windows 2000) to this day.
It could well be that your processor could be overheating causing the said problem. Check your heatsink and make sure that the compound hasn't set like a lump of concrete (rendering it useless) and have a butcher's at your fan to see if there isn't an inch of dust on top of it, Also double check the seating of the processor and other devices on the motherboard - heat induced chip creep can be a real bitch.
Ditch your win 98 though - even nostalgia has it's limits! PSsst got a nice copy of Windows 3.11 for Workgroups if you're interested
Si thee
