*edit* apologies. Forgot to mark as question.

Hi. Does anyone else have the following problem in this game and know how to fix it, please?

Okay, so.. I can fire straight up whilst simultaneously running to the right. However, when I try to fire up and run left, Hocus carries on running left without firing. In other words, can't fire 'up' and run 'left' at the same time.

The annoying thing is, it works fine using the Num-keys, but I normally prefer to use the arrow keys - which have this problem.
I did not notice this at first, then it seemed to happen on and off. Now it's always like this. I've tried re-installing it to no avail.

This fault seems to be DOSBox-related, as it's happening in Realms Of Chaos too :(

This is a general keyboard input problem that affects EVERYTHING, not just DOSBox. I would suggest you change your "fire" button to another key in the options menu and not use the Alt key at all. An alternative is to change the arrow keys to W,A,S and D keys with DOSBox's key mapper.