Try and sort the problem yourself first - you certainly won't make matters worse.
It is very likely caused by some nasties you inadvertently downloaded. Curiosity killed the computer. :)
Turn off system restore. Run your spyware and anti-virus programmes. As many as possible.
I recommend A2, AGV, Spybot, Ewido and Ad-Aware as a bare minimum. All of these are free.
Make sure you have a good firewall - I use ZoneAlarm, again free.
When you have finished turn system restore back on.
This is an excellent link to plenty of free utililty programmes:
http://cgi3.ebay.co.uk/ws/eBayISAPI.dll?ViewUserPage& ;userid=cuddly-hippo
And good luck!