http://tinkerit.googlecode.com/files/speech_daisybell.pde hangs on Arduino NG with a fixed tone

Reported by gomako on Cantarino group.

Write to TIMSK clears TOIE0. This freezes the Arduino millisecond timer, so delay() hangs.

Fix suggested - TIMSK write should only alter TOIE2 bit. gomako is verifying on Cantarino group.

Fix verified as working by gomako