Internet wont share anymore

Hi first of all im using, Vista on a sony vaio laptop
and for internet Im using a 3 internet dongle. For
ages now I've been setting my internet for local
sharing and connected my PS3 up to my laptop
via ethernet cable and going online on my ps3,
no problems there at all. I've been having a problem
recently where I cannot use the internet on my
laptop at the same time, this usually worked fine
before. I havent installed anything new to my
recollection to screw up my settings. Can anyone
tell me how I can use internet on my laptop at the
same time as my PS3 again? Any help you can give
is greatly appreciated!