that seems to be a G3 dongle. No, no-one else can access the internet through that unless (1) you are connected to a local network and (2) you have internet connection sharing turned on
You don't mention the version of windows on the machine, but in Vista or Win7 the error could be due to a conflict between the built in drivers within the operating system, and those on the dongle: both trying to control the dongle at the same time
Or it could be that your phone company is running out of IP addresses for the number of clients it has