Hi,
Update your anti-virus software and scan for viruses. You can get a free
online scan here: http://housecall.trendmicro.com/

Note the name of any viruses found and follow all removal steps exactly.

Free anti-virus software you can install:
http://www.avast.com/i_idt_153.html
http://www.grisoft.com/us/us_dwnl_free.php

After you have completely removed any viruses, scan for adware/spyware
with AdAware; you can get it here:
http://computercops.biz/downloads-cat-14.html

Also recommend you download and install Spyware Blaster, available at
the above URL also.

mm