Hmm got a real strange issue here.
I installed the game and at the last page of the installer you get the option of launching the game. I selected this option and the game worked just fine. I played through the first part, getting to Flotsam Island and then exited the game and went to bed.
Today I of course wanted to play the game again, so I hit the shortcut to launch the game and nothing. The monkeyisland101.exe appears briefly in the task manager and then disappears. I've uninstalled and reinstalled the game several times now and I can replicate the behavior I've described every time. The game will launch from the installer, but never from the shortcut or monkeyisland101 executable.
My system specs:
Windows 7 RC1 64 bit
Core 2 Duo @ 2.13 GHz
4 GB RAM
Nvidia 9600M GT