Just a heads up to everybody to be wary of suspicious emails lately. Yesterday morning I received 7 emails in the space of 3 minutes from a "MAILER-DAEMON@yahoo.com". I didn't open any of the emails just in case that could give them access to my computer in some way and fill it with viruses.

I then shortly after received an email from BT saying that "suspicious activity was detected on your account" and then instructions to change my password which I did immediately!

But yeah, just be cautious of the same things popping up on your email

is yahoo returning undelivered mail to you, Most likely your pc is/has been infected with a trojan that mails out to your address book.
run malwarebytes and see what it picks up and removes.
get it here: http://www.malwarebytes.org/mwb-download/
some more info can be found here: http://forums.digitalspy.co.uk/showthread.php?t=1826304

Ahh ok, I feel like an idiot now haha

I'm running the malwarebytes now! Thanks for the help mate