Pre-Dawn Account Hacker

[jamesson1980]

Today in my hotmail, I get this:

jamesson1980,

Your account on Australian Ford Forums has been locked because someone has tried to log into the account with the wrong password more than 5 times. You will be able to attempt to log in again in another 15 minutes.

The person trying to log into your account had the following IP address: xxxxxx

I can give you the offending IP address if you like, I really don't think it's my own. Can any mods shed some light on this? Is it common? It apparently happened at about 4:30am 21-12-10. The strangest bit is that I'm automatically logged on when I open Ford Forums and never really even need to enter my password. My concern is that it's some bug in my own computer which I'll have to hunt down, but I was hoping for a bit of a clue that I might be looking in the right spot.

Thanks in advance, and if this is common and I've created some duplicate feel free to delete this and point me to the right place

thanks again