system blacks out in the Shut Down process

[Dedi Landsman]

Hi, after upgrading a 9.04 Wubi to 9.10, there are problems with the Shut Down process, after pressing the relevant icons for Shut Down, the system blacks out, the screen gets plain black, but the computer won't shut down, it just got stuck, not responding to anything you press or the Keyboard, not even Ctrl+Alt+f2/f3/f4/F5/f6/f1 [in an attempt to Shut Down with commands] . in the end i had no choice but to plug of the electric wire [the computer is not in my house, i could'nt leave it working]. what could be the solution?
should this computer continue to try and use its current Ubuntu installation, does these "hard" Shut Down pose a risk to the Windows installed on it?
should i uninstall this Ubuntu ?
thanks for any help.