Firefox problem!

ok since monday i have been getting this annoying message when ever i start up firefox. its a popup saying that some site eg"adgkjasdfaaofdijsodifj.com" could not be opened.

i have cleared my cache and tried it and it still happens.
i have reset my webpage to google but it keeps changing.
i have also run adaware and spyware through to check for viruses or adaware. nothing showed up.
i have reinstalled firefox and still keeps happening.
and i have noticed that whenever i start firefox, an “iexplorer.exe” starts up in my taskmanager…
anyone else having the same problem?