Has anyone ever heard of a computer acting this way?

My laptop is windows xp pro., 1 gb RAM, Processor over 1 GHz,but
sometimes after clicking IE when I get on the internet above the
start button a little magnifying looking (I guess you might call it an
icon-or some kind of sign) will appear, and when it does my computer
goes very, very slow and I don't know if it would ever connect to a
website-because I give up and get back to the desktop, and I
try again. Sometimes it don't show on the second time-and sometimes it
will. I have put the arrow
down on the magnifyng glass, and and the reason it's there doesn't
show up. Has anyone ever heard of this before and what causes it?

James