A lot of people seem to have trouble with windows 98 power management.
My computer tends to go into a deep sleep that may wake when I press a key but the scheduler is unable to wake the system to run tasks.
I would suggest that you check the power management trouble shooting
information on Peter Forrest's web site.
There is a power trouble shooting area on the microsoft site.
You might also try asking in the usenet group
Also from a post by Peter Forrest in alt.windows98
Power Management related links.
Try the APM Troubleshooter. There is a copy on your Win98 CD
but there is a better one available from Microsoft's web site:
Troubleshooting Power management lack of Suspends and Resumes
Computer Hibernates When Standby Is Pressed
Hard Disk Is Active After Windows 98 Shutdown
Monitor Is Energy Star Compliant Check Box Is Unavailable
Computer Does Not Resume from Standby When USB Device Connected
Cannot Suspend Computer If Secondary IDE Drive Is Not Present
Computer Is Unable to Go to Standby Mode
Standby Missing From Windows Shutdown Dialog Box
Computer with Accelerated Graphics Port Hangs After Suspend
"Hot Corner" Features Do Not Work in Windows 98
Error Message: Error Loading Powrprof.dll
IBM Computer with IDE DMA Hard Disk Hangs When Resumed
Auto Insert Notification May Prevent Automatic Suspend