I can ping but not be pinged (Hamachi)

[Senor Snarf]

I have no idea what the problem is. I'm trying to play a few different games with my two friends over Hamachi but no matter what I do, I can ping both of them but neither of them can ping me. This results in myself lacking the ability to host any games. I'm totally stumped. I've tried so many things and all I can think of is that it must have something to do with my router. Has anybody had a problem like this before?

 

[sturm]

Check your router or modem and see if it is allowing ping responses.