Quick question, does your company have a BES? (Blackberry Enterprise Server)
With the redirector you need to make sure that the Redirector window is open and stays open and is never closed. Make sure that your computer is always on and connected to the internet.
You can plug the device into your computer and go into redirector settings and then security and re-generate and apply the encryption settings 3 times.
Also sometimes leaving your outlook open will help as well.
What OS is your Blackberry running, latest for the 7250 I beleive is 4.1.353 or something close to that, if t is older than that you can upgrade the device OS by visiting BlackBerryâ„˘ 4.x Software Download