Please could you give details of the McAfee product(s) you have installed, and confirm that you have run an update of it/them?
When you say you are sending out emails to all your contacts, could you describe how you came to find this out? There are plenty of viruses that can spoof the 'sender' having harvested that e-mail address from someone else's machine.
Have you run any scans ?
Did McAfee alert you about any trojans ??
Do you feel that your ocmputer bogs down to a standstill and takes forever to do anything ???
Please update yoru AV software and run a complete scan and please post the findings here !