My wife's computer: She normally goes on the internet using google.co.uk as her home page. Now, every time she clicks the Internet icon, it switches on the browser (IE8, and Vista) at google.co.uk, then promptly switches to google.com, and a warning that cookies are disabled. It gives links (which I dare not follow yet) to instructions for sorting out the problem. Microsoft Security Essentials full scan finds no malware. Attempts at System Restore find only one possible restore point (when she switched on today). A Yahoo symbol has appeared on the browser. What's happened, and how can she get back to normal browsing (and Gmail)?
A common reason for Yahoo to appear like that is if you install a piece of software that also installs Yahoo for you as a side issue. If you don't watch carefully during the installation process and click 'no' when it asks you, you'll get Yahoo installed.
Thanks for the warning, Ian in Northampton. I know she usually looks out for those checkboxes, but she may have missed one this time. Prevention is better than cure, eh? Unfortunately, we still haven't found the cure. I'm having another go at it this morning.