MacOS – Copy and paste stops working

For several months now i've had an issue where after using my laptop for a couple of weeks without restarting, i'll slowly lose my ability to copy and paste. First it's only between different apps such as Terminal and Sublime Text, but eventually it's system wide and stops working everywhere.

As I type this, nothing seems to be copying to clipboard. Not in textedit, chrome, safari, terminal or otherwise.

Going in to Finder > Clipboard shows only one small piece of text which is the last thing I successfully copied before it completely stopped working.

Should I dump a process list here to show what i've got running or is there a common issue that could be the cause?

I'm on a 13" retina macbook pro running 10.9.

Thanks

Edit 1: It's drag and drop too.

Edit 2: After trying a million fixes found on the internet (changing file permissions, /private/var fixes, disabling hidden files from showing etc, killing third-party processes one by one), none of it worked. I did find however that killing the WindowServer process, which esentially closes all windows and resets the GUI, does provide a bandaid "fix" to the problem and bring copy&paste/drag&drop back. However, this is not particularly surprising. It's almost as inconvenient as simply restarting, which was my old fix. Still would like to figure out the underlying cause. My main suspect is the Windows apps I run via Crossover are messing with something in the system, even after killing Crossover and their processors.

Edit 22/6: I will post a process list and result from kextstat | grep -v com.apple once the issue arrises again.