Desktop icons disappear and then reboot

Can anyone tell me what this problem is and how to overcome it?

About 4 or 5 times during the course of about 4 hours each day on the
computer the computer will sieze up and the icons will disappear from
the desktop and then immediately start to reappear (sort of a
rebooting). The whole process takes about a minute (I have Windows XP
and Internet Explorer 8) during which time I must sit around twiddling
my fingers.

How do I fix the problem?

I thank you in advance for your attention to this query...