I'm having the same problem... Upgraded my internet service and changed routers on the same day I installed 2.03 so I wasn't sure if it was my hardware or GT, but it seems to lock up whenever it would be connecting online... either it locks up just before the online terms, or at the main menu with no cursor to go to my home. In the odd time that I can get it to load it might work for a while but freeze on the GT screen when returning home after a race. Other online stuff seems to still work when this happens (PS store, internet browser).
Sorry for the ignorance, but how do I back up my save data and start GT5 offline?