Right, so, this has already been posted in the dedicated Postal boards, but I guess not enough people read those boards or are even into the game itself to have bothered finding an answer.

Anyway, while pressing the Right Arrow key to Rotate Right works just fine, pressing the Left Arrow key to Rotate Left does not. For some people, apparently, pressing Left Arrow produces no action, while for me, pressing Left Arrow twice rotates me left maybe one pixel. I've tried playing with my XUSB controller unplugged, but that doesn't produce any new results.

On the plus side, rotate left and right by moving the mouse left and right still works just fine.

If you take the numlock off, does the keypad left arrow work properly?

Isn't that just a hardware issue ? Sounds an awful lot like the good old "can't jump/shoot to the upper-left", caused by an old keyboard...

Not old, cheap. Modern ones are the same, they're only made to register 2 key inputs at once

More like 5 signals at a time or something... I guess one of the reasons wsad is/was so popular is/was because it only send one signal instead of two.
I still cannot figure out how the "left arrow" two signals are different from the "right arrow" two signals, though :\.

Still - you can't go wrong with getting a gaming keyboard, no matter the reason ;P.

I tried it with Numlock off, no change. And it's not a cheap keyboard, it's a Logitech G19. How is one key two signals?

It's a known bug of the game, I had the same issue when I tried to play it. I did some research and, at the time, the only answer I got was that there was no solution other than trying to play the game with the mouse.