Fingerpint Reader problem

Most of the time, after I have logged in my account (administrator) stops
working after a while.
I cannot use it in any web page. It requests that I identify myself with
one of my fingers, but
this won't work. I cannot open any of the fingers to reregister my
fingerprints.

I have to close the session and reopen it. It then works (for some time).

Anyone ca explaint that and hopefully offer a solution ?

I use Windows XP Pro.

Thanks.