I know that in 4th edition, you're allowed to make an Intimidate check against a bloodied enemy to send it running.  As far as I've seen in the rules, there doesn't seem to be any real limitation other than this.  What should I do if a player chooses to max out their Intimidate score to take advantage of this?  Should I always allow it, or case by case?  What about situations with elite or solo enemies?