Encounter! ~ My movements are not behaving.

[Atari Calimari]

I'm playing Encounter! and here's the problem. While moving forward/left (diagonal) and fire at the same time it won't let me fire. Same thing with down/right and fire too. It's irritating! Movement in other directons and firing works fine, just those two are having problems.

The thing is, I remember playing the game on the original system and don't remember it ever "acting up" on me like this. I could go in any of the 8 directions and fire simultaneously. But for some reason while playing on the emulator it's not wanting to let me travel in those two diagonal directions and fire at the same time.

The emulator I'm using is Atari800Win Plus 3.1 and I don't have a real joystick. I use keyset A with the arrow keys set for the movement and spacebar for fire.

Another thing I should mention is that my computer is an HP mini. It doesn't have a numlock key and a number pad. Could that be part of the problem?