Monitor shuts down while switching users

I just installed windows xp pro SP2 on an old 366 Mhz pavilion I had sitting around....The system is running incredibly good, in fact better than I could imagine it was going to....Just one problem that I have never encountered before; Every time I switch between user names the monitor shuts down or goes to standby and then comes back up......Anyone else encounter this problem before???? Any Suggestions??? I know that I am asking a lot of this small machine but I am very very satisfied with the 366 MHZ , 128 MB pc100 RAM machine's performance so far.....Thanks in advance for any help or suggestions...Have a great day..:D

Set all of the users to the same screen resalution. I have seen this before and it is because the screen is being sized to the new user settings.