Problem with samsung Corby S3650W

i'm having difficulty with this fone. just bought last friday.
i connected it for the first time on our wifi at home...it worked, it got connected...then when i tried using twitter and facebook on my fone, all it says network failed.
then, i tried connecting it again the following day, it said "connecting" then a few seconds later, it said disconnected..
now i dont know what to do with this fone!

Windows XP