It sounds like you need to scan your computer for viruses and malware A trojan is a nasty file that has sneeked onto your computer without you knowing whilst you were surfing the web! Try download a free program off the internet like spybot search and destroy or Malwarebytes Anti malware. then once downloaded update the program then run a scan. It should find these trojans and destroy them off your computer!
Hi, thanks for that... we have Virgin Media security and I have scanned ... said there are no viruses... is this now ok? Think the Trojans are now quarantined?
If VM security flagged it up then it should have dealt with it. Malwarebytes as RAVID suggests would be an excellent idea though.
After that do a system restore and see if your Google tool bar comes back.