>>As far as I know sys(0) returns "computername#username".
>>
>>

>> cComputerUser = Sys    (0)
>> cComputer     = Left   (cComputerUser, At ("#", cComputerUser) - 2)
>> cUser         = Substr (cComputerUser, At ("#", cComputerUser) + 1)
>>
>> MessageBox ("ComputerName: " + cComputer + " User Name: " + cUser)
>>

>
>This much I do know. The problem is that the SYS(0) is NOT returning the current logged on user, but the user name that was assigned when the OS was installed.

Maybe you (or someone else) changed the user name from "User" to whatever it is now:

http://answers.microsoft.com/en-us/windows/forum/windows_7-security/how-to-change-user-name-in-windows-7-professional/d95ddaa7-4235-454e-83d6-77232207c7e2

A name change is cosmetic, a lot of underlying stuff doesn't get changed. If SYS(0) is relying on something that doesn't get changed, that might explain what you're seeing.