Did you try any online Virus scans?(The following require Internet Explorer to work. Watch the Address bar in IE. You may receive alerts that "This site might require the following ActiveX control...Click here to install...". Click on that alert and then Click Install ActiveX component.)BitDefender Online Scanner
<- Add a check by "Autoclean"
.ESET Nod32 Online Scanner
<- Vista compatible but Internet Explorer must be Run as Administrator
.F-Secure Online Scanner
<- Be sure to follow the directions on the F-Secure page for proper Installation.
(also checks for rootkits
Check to see that your computer is set to the correct date. If it is, then an uninstall, re-install of McAfee may be necessary. I have read numerous complaints the same as yours and that seems to be the recommended solution.
If uninstalling via Add/Remove Programs
does not work properly, then download and run the McAfee Consumer Product Removal Tool (MCPR.exe)
which removes all 2005, 2006, 2007 versions of McAfee consumer products.
I don't use Yahoo Messenger so you may want to contact Customer Care Support
for assistance with that issue since, uninstall, re-install did not help.