Maybe I am in the wrong forum, please direct me to the more suitable.
For example, after installing some free software, you can easy get this situation - you have cleared register and files, but EVERY time you open browser, you have new tab with specific web-page opened.
The reason is simple:
program link is this like
"C:\Program Files\Internet Explorer\iexplore.exe" http://www.mystartsearch.com/
So, it is very nasty, and also very easy to detect and not a problem to solve.