Are all the storms on the latest software? I have our only Storm
and it is fine but mine is a 9500 (in the UK).
I don't suppose you have a different BB to test this with do you? Could be a user issue but that could take forever to find without a benchmark.
If the Storms are all on the same version why don't you put a "bad" user on a "good" user's Storm and see what happens. At least you will know if it's user-specific and can naroow down the troubleshooting.