WeLL everyone i am going to give you a very good walkthrough on how you should go about fixing this problem this is what i did, if your pc and PS3 ip address are close to each other there will be an ip conflict so you need to make one for your PS3 so thatyour pc doesnt boot your PS3 from your router here it is hope it helps
Btw its not the NAT type your fixing its the ip conflict (but everyone should have NAT TYPE 2) just try it and see if works.. DID FOR ME !!
PreGameLobby - How to get a Type 2 (Open) NAT on your PS3