DOH!
running windows xp with all the sp's and internet security updates. The ISP is throught telewest broadband but my desktop is run through a wireless router from a main desktop in another room which has the same dam problem! Again its running the same stuff.
I've run adwear se and it finds stuff which i delete, then run it again which then confirms all to be clear but when i open IE and try to go to my email which is yahoo, it gets hijacked again! but only when i enter my user name and password.
It however dosen't happen on the laptop i'm using, conected through the same router and can access my yahoo email no problem.
hmmmmmmmm?
oh, the router has a firewall and one system is using norton and the other norman virus scan.