BB Torch :: 9810 Touchscreen Occasionally Freezes After OS 7.0 Update

I have recently upgraded my phone to the updated OS 7.0 Bundle 2406. My touchscreen occassionally freezes and does not respond for sometimes 15 minutes at a time. I do not recall if my touchscreen used to freeze before the update. However, I have tried downgrading back to the old OS and this does not work. Very often the touch screen seems to freeze after disconnecting from the USB cable connection to the PC or the bluetooth I use in my car