How much memory in the computer?
How much memory is being used at the time it goes blank?
(Your XP version of Task Manager may have an advanced button in Task Manager that will give you some of this information. Alternatively I believe there are some smaller XP Utility programs that could help you to find out.
goes blank sometimes when it is running out of memory or doing something intensive.
Are any other program open?
Can you shut down any of those, including startup programs?