Firefox and spyware- help needed please

Hi
Can anyone help with a firefox problem?
For some weeks now I've been bothered by some sort of bug/tracking device that has infiltrated my firefox web browser.
It doesn't do it everytime I start up firefox, just sometimes. It opens up one or two new browser windows along with the one that I have just opened and tells me where to find vodafones or some other product I'm not interested in.
I have read up on this on web pages and have used spybot search and destroy, ewido anti-spyware and some other devices but these programs can't locate it.
I've been advised to empty my temp. files, but I'm a bit reluctant to do this as there may be things in there that are keeping other things going and there seem to be lots of temp files on my pc anyway.
Any suggestions?
Ben's Dad
Can anyone help with a firefox problem?
For some weeks now I've been bothered by some sort of bug/tracking device that has infiltrated my firefox web browser.
It doesn't do it everytime I start up firefox, just sometimes. It opens up one or two new browser windows along with the one that I have just opened and tells me where to find vodafones or some other product I'm not interested in.
I have read up on this on web pages and have used spybot search and destroy, ewido anti-spyware and some other devices but these programs can't locate it.
I've been advised to empty my temp. files, but I'm a bit reluctant to do this as there may be things in there that are keeping other things going and there seem to be lots of temp files on my pc anyway.
Any suggestions?
Ben's Dad