Windows 7: Error 720: Connection to remote computer not established!

I recently bought a PC running Windows 7 home premium which was running perfectly fine until out of nowhere 2 days ago. My Internet is Dodo wireless and all of a sudden whilst connecting and getting to the "authentication" stage,a message pops up saying "Error 720: A connection to the remote computer could not be established." I have been reading other help forums and proceeded to install the latest Realtek driver,restore to a previous working point and un-installed programs which I though may have contributed to the problem but to no avail. Please help,formatting is not an option as the guy i bought the PC off didn't supply me the install disc! Cheers all!