72 hours and no reply from Steam support (AOL Blamed) ?

[Troll2k]

Somehow Steam gets a hardware image of you machine when you install it.If you try putting Steam on another machine, they know it and think someone is trying to hijack your account so they send a verification code to your registered email address.However this code is very time sensitive and if you do not enter it right away it becomes no good and you have to get another one.

This also occurs if you change your hardware.Like upgrading your video card or cpu.