Cant open attachments HELP!

Hello,vista basic, office 2007 installed.... recently i have been unable to open any attachments to my tiscali emails,..just goes to empty download box, so when i try to save as...message on screen says ..internet explorer cannot download, no such interface supported. ive no idea what this means ,is there a fix to this . thank you (installed McAffee a few weeks ago could this have anything to do with my problem)