I try to move with arrow keys and numpad, both result in the character jumping around. This makes combat basically impossible to play.
I play the game using the dosbox and conf file that come with it.
Any way i can fix it? Or maybe someone can share me a proper conf file?

Also i notice that sound only work if i choose AdLib instead of the recommended Roland.

Could it be that the Caps Lock key is on? I don't have the game installed anymore nor the manual on my hard drive so I could be talking through my hat but a quick search for the controls seems to indicate that the keyboard controls for moving are the numpad keys, and jumping is shift+numpad. The only thing that comes to my mind is that maybe the Caps Lock key is on and the game thinks you're jumping around. Beyond that I really have no idea.

Caps Lock is off, and it doesnt seem to change anything even when it's on.
I do found a temporary workaround though. If I use shift+numpad the character can walk normally. My current guess is that this might be a hardware issue. (I'm using a USB numpad).

Pretty sure it's Num Lock that needs to be toggled, and you need to use the numpad. The arrow keys will just make you jump. And it is correct that shift+numpad will make you jump, if it's working right.

Weird that Roland sound is the default, because Roland doesn't just "work" automatically. Since AdLib works, use it.

I always play combat mission with numpad, and the numlock is always on. If i turn it off I jump around even with shift+numpad. I can only walk when the numpad is on and I press shift + numpad.

Another strange thing i found is that after i use shift+numpad for walking, there is a chance (like 30% chance or less) i can walk normally with numpad only, but it change back to jumping after a minute or so. Very strange.