Well seeing as you havent provided much insight into the Hardware aspects of your machine,, I will try and work in virtual terms...
The problem with Standby is that XP takes a "snapshot" of everything that you had going,, and saves this snapshot in RAM and HD memory.
When you come back and hit a key,, any key,, pick a key,,, you start up the wake process, if your machine is lower end in HD space, RAM, or processor power,, Standby will give you a headache.
My suggestion would be to either a) lock the PC using CTL-ALT-DEL , this will maintain your pc in the present state
I have a feeling that there is a patch for Standby, however, I personally disable that feature on the bulk of XP machines due to the problems as you have stated,,
MCSE, MCP+I, A+
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