Yahoo email sending unsolicited emails from my account

[richardfinch]

Hi, my yahoo email address seems to be sending emails every now and then from my email account to everyone in my address book (and automatically putting the sent emails into my trash folder from my sent folder). Ive run all my antivirus and changed my password, and its still happening, ive contacted yahoo, who tell me to change my password, when i have already done this - can anyone else advise how i can stop this happening??
thanks
richard

[AlBags]

Do a full PC scan with System Restore switched off.
Empty out all temp folders/files/Temp Internet files.
Change password again to a long one with numbers/letters/Upper/Lower case.
Do you use a PC installed client to access Yahoo? .. or access/store directly on the web?