Problem with internet access on my ps3

Hi i am having a problem logging onto the internet via my ps3 i run my internet access through the public access facility ang untill last week this worked like a charm but after leaving my ps3 at a friends house i can not log on all i get is a white screen then a dns error pops up.

When i check the settings it says i am connected to a belkin54g which is what i have always connected to my signal strenth is between 25/40% not the best but i have logged on before with a lower strenth address are automatic but sometimes under ip address it says private network only which i do not understand and at the bottom it tells me the nat type has failed.

Can anyone offer any help on this subject apparently my mate was surfing some sites could i have a virus or something. please please help cheers.