Programmer is not Responding

Hi forum!
I'm new to microcontroller programming, but i got an arduino Duemilanove at Christmas so I did a few things with it.
As for now I just tried to play PCM sound trough the PWM output using this (arduino.cc/playground/Code/PCMAudio) tutorial.
The problem is, that after uploading the code with the real big array of sounddata, the yellow "L" LED is blinking fast and the programmer is not responding.

Im worried that i may have overwritten the Bootloader with my code (our some RAM issues), but the Problem is, I dont know how to get rid of this behavior as the programmer is not responding.

MFG Dunior