Safe Mode Help

I have recently upgraded to XP Professional. My scanner
is now not working. I went to the manufacturer's website
and downlaoded the lasted driver. The instructions tell
me run the pc in safe mode by hitting the f8 (during the
boot-up process) key 2 times per second to get to the
start up window and then select 3. I have tried to do
this and no start up window appears. My pc just reboots
as normal. The only way I can install the driver to work
with the XP is in Safe Mode. Please help.