I have been getting strange emails with numbers and letters in the subject line, and people in my email address book have been sent these same strange emails from my address - that I did not send. I must have some kind of virus but when I run McAfee it detects nothing!!! My computer is not acting right either, running slow, msn email is freezing & going blank and I can't get into my files on my external hard drive! Any suggestions?
Certain malware can mimic your address and send emails from anyone who happens to have your email address on record, so the chances are it isn't you.
Try scanning with Stinger and Malwarebytes Free, both are linked in the last link in my signature below, but to keep Malwarebytes free of charge you must NOT accept the trial offer.