9330 Tethering Issue when disconnecting,

[fremont]

I have a company Blackberry 9330 that my company just gave me to replace my old 8330, which worked great until the track ball wore out. We use the tethering feature and Verizon is our carrier. What happens with the new 9339 when I disconnect from tething, it locks up the phone from the data connection. You have to pull the battery out and reboot to get it to work again.  I've spent hours working with our I.T. department and they can't figure out what is going wrong. They even sent me a replacement phone. I've tried this on two different computers, three different USB cables, Wipe and reloads, and software updates. Nothing seems to be helping.

Can some one help correct this issue?????