If it's a desktop, simply hold in the power button on the tower for about 5 seconds, let go, and push it again to restart.

Restart the system as the previous message states, start in safe mode, go into the control panel, power management, uncheck hibernate.

i know this thread is a year old, but anyway...

is that usually the only problem?

i'm having frequent problems with returning from standby.  almost always i have to restart the computer.

 

is there a good way to troubleshoot whether there is a program preventing/hindering xp from returning from sleep/standby?