After hearing Bush still didn't know whether he was alive. Osama himself decided to send Bush a letter in his own handwriting to let him know he was still in the game. Bush opened the letter and it appeared to contain a coded message:
370HSSV 0773H
Bush was baffled, so he e-mailed it to Condi Rice
Condi and her aides had no clue either, so they sent it to the FBI. No one could solve it so it went the the CIA then to NASA.
With no clue to its meaning, they eventually asked Britain's MI6 for help.
MI6 cabled the White House:
"Tell the President he's holding the message upside down".
