you don't give us much to work with!. Make of laptop, operating system, which firewall would be a start. It could be a conflict of software or hardware, but could also be caused by malware (viruses, spyware etc.)
go here
http://www.lavasoft.com/ and download the free version of ad aware. Then here
http://www.spybot.info/en/download/index.html and download the free Spybot search and destroy. (Please donate if you can. I am not in any way affiliated with this site or product, but they do an excellent job and our support is what will keep them going and free).
You do not say if you have an abti-virus. If not go here-
http://free.grisoft.com/doc/avg-anti-virus-fre e/lng/us/tpl/v5
and here
http://free.grisoft.com/doc/ewido-anti-spyware -free/lng/us/tpl/v5 to download the free antivirus and ewido. Update the definitions of all these programs and run them in safe mode. Let them remove all the malware they find, then try again. Post back if further help is required. I will do what I can.