This is a strange problem.
From the menu screen select options. Something keeps cycling up.
When I go to use the toolbox put away and take out keep cycling.
When I try to select a weapon that menu keeps cycling with no way to stop it.

I unplugged my keyboard, mouse, and all USB devices and it keeps cycling.

I had the same problem (Steam edition, though).
Turns out the game has a HUGE problem with controllers. Immediately after I unplugged my controller everything worked just fine.

I already unplugged my keyboard, mouse, and all USB devices and it kept going. The only controller I have is an N52te. Do I have to uninstall the profile editor as well?

Edit:
Looked at the Steam forums (why do those pages load so slow?) and saw a topic about infinitely-scrolling mouse wheel. A post lead me to <span class="bold">this fix</span> which is working for me.