Here is another fun solution to the halting problem:
Machine F time travels to future, catches Alan building G, kills Alan, blows up G, G never came to be and that rhymes.
PROBLEM SOLVED LOL.
Time travel is very real in virtual machines, check VMWare and it's snap shotting features and it's VM Deletion feature ! =D
Bye, Skybuck.
P.S.: The moral of the story, if Alan is allowed to time travel and build G after F then F is allowed to time travel too ! =D HAHAHAHAHA.