Comment 1 for bug 1248899

13.10, 64bit here.

This might be something to do with Unity, since if you switch to Gnome this issue is no more affecting me.

In Blender it is reproducable like this:
1) create a cube and select it in object mode;
2) now hit on keyboard G (for moving) and Z Z (yes, two Z's in a row without pausing in between)

What should happen at this point is you should be able to move a cube along its local Z axis, however you will notice that after hitting Z two times it shows the local Z axis only for fraction of a second and then cancels it allowing you to move object freely.

The only way to get around is make a pause in between these double Z keys. Like one second or something like that. Then it works.

Same story about all other shortcuts where you are required to hit one key two times in a row.

Things that didn't help: reinstalling unity, messing in all possible ways with keyboard settings, universal access bounce option on/off. So basically I've ran out of ideas.

Can confirm that nothing like that happens in 13.04, 64bit.