When I tried 4.5 I too lost GPS on my 8310 so I wenr back to 4.2.2 and then I had to got to Options, Advanced Options, GPS hit MEnu and select Refresh GPS. After a fair time (dunno exactly) it gave me a position again.
Check the gps options, mine was disconnected, then, go to option advance applications, google maps edit permissions, check if connection and user data are still allow.
Otherwise I have a couple of issues:
1.-I can not activate A2DP with mi blackberry curve 8310 and Motorola Bluetooth HT820 when play any video, it works just under version 4.2.2
2.- Recording videos in 2 of 10 the BB rebooted
It won't keep searching for 10 minutes in the GPS utility that comes with the OS...
I no longer get the error but it won't lock onto a location...
I am going to try Google Maps to see if it will lock on...
You can also go to google mobile on your pc and it will send the updated google maps directly to your phone for download you can also get google feeds, mail sync and other apps this way that's what I did after my 4.5 upgrade