Make a directory C:\Hijack
Go to the following site, bookmark it & download Hijackthis to the directory you made.
http://www.hijackthis.de/enOpen the Hijack program, run a scan, save the results, go back to the bookmarked website, browse your computer for the log file you saved then get the website to analyse for you.
You may also want to paste your logfile in here but it's a bit fiddely because you will have to paste it in 3 pages due to it's size.