Some help with this would be appreciated.

I can only place items in weird cross shaped patterns. When I try to place them anywhere else, they will either get placed on the axis or get placed, play the plunk noise, then instantly return to my inventory. Moving or choosing a new item seems to change the origin point.

Example: http://imgur.com/a/Lbwy8

This cropped up a few times before. Reloading the save fixes the problem. However, this time the autosaves are all like this and the only manual save I have is several hours back.

Any suggestions?

Press shift f, you enabled cursor lock by mistake. The hotkey for it isn't that great so if I get around to finishing my tiles update I will probably change the default. Not really sure what to, though.

Thank you so much. My mind overfilled with 17 different ores and 9 million gasses... I didn't manage to figure this out. It makes sense that it's a mod feature and not a bug; only build belts in straight lines, etc.