Sorry for the lack of detail. I have used both the McAfee Virus Scan and the Scan by the anti Spyware program Spyware Doctor 4.0. The second of these recorded 7 Trojan infections a few days ago which when present had the effect of directing me to an unwanted web page. All now is deleted. I was initially directed to an unknown web site but mangaged to get it back to my desired(Yahoo) by downloading the Yahoo Toolbar which had the effect of changing it to back to Yahoo! However the problem described above still applies and the address on the bar to change the Home page in Internet Options is faded out (grey).

As a matter of comment I have found that in spite of the claims the major anti virus programs rarely detect any Spyware yet when I run the Spyware Doctor scan mentioned above I can easily score over a dozen infections each time!