Try adding -showscripterrors into your Arma2 shortcut target line, after that the game should show scripting errors on the screen.
Regardless of that all errors are stored in a arma2.rpt file which is stored in a folder (can't remember if it was a hidden folder or not): in XP user\Local Settings\Application Data\ArmA 2, in Vista/7 user\AppData\Local\ArmA 2.
As far as I know sqs scripts should work the same although it's kinda outdated, sqf is the way to go..