A few weeks ago we came upon a bug in BBOS 7.0 after deploying a new IT policy to a small subset of our users.
Some of the devices in the test group BlackBerry were very slow, sometimes unresponsive and had a very short battery life. Reverting back to the previous policy solved the problem.
While investigating the cause of these issues we noticed that all the devices showing problems were running OS 7.0. An upgrade to 7.1 fixed the problem. We quickly found the cause, described KB28750, to be a specific issue in 7.0 and IT policy settings related to NFC.
Moral of the story is that you should test changes to the IT policy on the most common OS versions found in your BlackBerry population when deploying changes to your IT policy.