Over the course of yesterday and today I have been creating an image list of the vehicles, so I know what they are in the vehicle list (I'm up to 58 vehicles). This means I have been holding RMB, pressing Q, then hitting "i" twice (hide gun and reticle), then pressing PrintScreen which brings up Lightshot (epic bit of screen shot software) then saving the image. When I tab into the game again I need to press RMB one or two times and hit i once or twice to fix the HUD and walking animations. However this seems to have messed up my ability to hold items, when I dropped my gun (The hand cannon) and tried to pick it back up I... couldn't. I was in Acrityrda (Dark Keigan caverns) at the time trying to unlock a new shell which didn't work, which is why I dropped the gun. Since then I've restarted the game a couple of times and today downloaded and am now playing the hotfix. I've looked through the appdata files as I believed it to be a problem caused in there (which would account for the complete game-change(just to specify, I have not edited any of those files)) to no avail. I've tried picking up weapons all across Terrahypt, inside of and outside of buildings :/ I'll try a complete re-start of the appdata folder (creating a backup ofc) and re-downloading the whole game pre-patch. I'll make a note on my findings here.
Well, sometimes you just need to write about your problem to find a fix, removing the Zerahypt appdata file sorted it out, I've restored my vehicles file and everything was running as normal again, so I decided to put my original save back in to see if it'd still happen... it works again. Strange bug with a strange fix, remove your save, run the game, close the game, put save back, profit.