Problem with the block/keep blocking on Windows XP!

[Akio]

Okay, my friend has ran into a problem with the blocking and keep blocking thing in Windows XP. He pressed Keep Blocking on accident and can't get the game back. We've looked for ways to unblock it but can't find it. We tried reinstalling it, but it still is blocking it. Is there anyway you can unblock anything?

 

[Geeke19]

are you using the XP Firewall ?