>>A couple of reasons could be:
>>
>>1) Your colleague may not have administrative rights. Even it seems the time was set, it was not.
>>2) There is a program running that update time with external reference time.
>
>Yes, in this case it was #2: Windows itself was set up to update the computer time. The reason the time was wrong is because the wrong time zone was selected.
>
>This may happen with Windows XP, too; it has the built-in capability to update the computer time.

Do you mean, something like "Automatically synchronize with an Internet time server" in the ControlPanel-->Date and Time ?