Software freezes at "uploading to I/O board"

I am trying to upload my program to communicate with an GPS module. When i press upload, the software says: "uploading to I/O board". Under it, it says that I use 5502 Bytes of 258048 maximum. The Leds show some activity.

But at this point it freezes. Only the Tx LED shows an occasional blink.

When I upload the example program HelloWorld.pde from the LiquidCrystal Library, it uploads and it works alright.

When my partner uploads the GPS program, it works alright.

I have windows 7, 64 bits. I have an Arduino Mega 2560.

My partner also works on windows 7.

Thanks in advance.

I try use the 64bits on ubuntu 10.10.
But I’ve the same problem.
Well then I installed the ubuntu 32bit and my problems ended.

look if in your code you have a string like this "!!!"