I was having all sort up problems with the ICS update. Severe Lag switching between screens. Internet access would just lock up.
Received a phone call from Verizon Tech and he told me that a hard reset seemed to take care of the problems. He advised doing a back up and removing the memory card and these instructions:
From a home screen, select All apps (located at the bottom).
From the All apps tab, select Settings.
Select Factory data reset.
Select Reset phone.
If presented with unlock screen, draw / enter the required pattern, PIN or password.
Select Erase Everything.
This has resolved all my issues. I did have to reload a few apps but the phone responds faster and the battery life has improved a lot.
I also was having problems after the ICS update. After reading some of the posts on this Forum, decided to do a Factory Reset. Backed up everything and reset the phone. Now all the issues I had went away and the Phone works great.