I have BB Curve 8310 and recently updated the OS to 4.5
I have had no problems except now when ever someone that I have stored in my address book calls It does not show the name and only shows the phone number.
Try a battery pull and see if that works. Seems to fix a LOT of issues. Anytime I make a change or have an issue, I try that first and it seems to fix 99% of my problems.