iPhone Keeps Locking Up

I just recently updated my iPhone to version 1.1.1. Whenever I press sleep/wake the slide to unlock appears and the phone locks up for approximatley 5-7 seconds, then I am able to slide to unlock. It randomly locks up for 5-7 seconds during normal usage and locks up EVERY time someone calls me, leaving me anxiously awaiting it to unfreeze so I can answer a maybe important phone call.. This is very annoying. Any one have the same problems?? I am curious if it is because of my use of 3rd party apps before I updated. I tried to restore, didn't help... Maybe version 1.1.1 is buggy? If you have any other ideas/comments on what this could be or how to fix this I would greatly appreciate it!!!!