Question to hackers/programmers

[Shigshwa]

I have a friend on MSN messenger, and he somehow can type a message using my name, but it's not me or my computer because:

-When writing multiple messages, it shows as bullets rather as separate messages. This shows as separate messages.

Proof(I'm the one with the longer name)(NSFW):

Spoiler

If you think I really said this, then you fail.

How did he do this?

 

[Ho-oh]

HOLY FUCK WINDOWS 7! I WANT.

I don't use MSN, or any instant messaging for that matter (old school FTW), so I can't help you there.

 

[Serpentsounds]

Either there is some sort of backdoor installed on your computer, or possibly he knows your login info. I sometimes get a notification from MSN about being logged on from 2 locations, but I'm not sure if that could be used to replicate this scenario. If he has access to your user account (on windows), then it's also possible that he could be using that to manipulate your messenger program.