Units Not Obeying Orders

So, I have a map where a lot of units are at once all ordered to do something. This seems to work fine except for the following problem:
Occasionally, the player controlling these units will NOT be able to control the units after they have been ordered. Giving them any order of a type other then the one issued via triggers, will cause them to stand still completely, and not acquire targets.

The real strange thing here, is that even units who were NOT given the 'mass' order will still not respond to commands. This generally lasts about 5 seconds, but it is an insane pain in the posterior. I'm trying a few things out to see if they will work (And haven't tested yet). The first is issuing the commands in spaced out waves. I already pretty much optimized the basic code for telling them to do what they have to do.

Anyhow, if anyone knows whats causing this weird bug, I would LOVE to hear it.

Without a map, or at least more specifics (how many #'s of units), I doubt anybody can be of any help to you. You're going to have to give us something to work with.