Anyone know the reason why the trial version of Windows 7 Enterprise is no longer able to be activated once installed.After the install when I go to activate the OS I now get a message saying that MS have blocked the key.I have tryed both the 32 and 64 bit option with the same result - cannot be activated

Theres no info anywhere about MS no longer offering the 90 trial and it's still downloadable from here http://technet.microsoft.com/en-nz/evalcenter/cc442495.aspx?ITPID=sprblog so looking for an answer.