Sorry for your problem and all the BS responses you received in this forum.
There are some really good people here but there are also a lot of
troublemakers that put everyone on edge with their constant trolling. I (and
others) experienced a similar issue with an old Linksys USB network adapter.
The main difference is disabling and re-enabling the NIC via the device
manager would cause it to reconnect. One brave soul upgraded to the Vista
version of the drivers but I never saw a response to know if it was
sucessful. In my case, I chose the coward's way out and bought a new Belkin
USB network adapter (not my first choice, but their PCI version wasn't Vista
compatible). For me, problem solved.
With that said, obviously something changed, be it something external to
your system or your system itself. Do you remember any driver updates before
the NIC started failing (check Windows Update History if you didn't
intentionally install anything). Also, if you want to isolate your hardware
and drivers, get a USB NIC and see if you experience the same issue. If the
issue then disappears, you can be more confident that it is your hardware or
drivers causing the issue (and not Vista). Also, with five signals that might
be considered a "saturated" environment depending on what channel everyone is
on. You may want to consider monkeying with your router and find a quiet spot.
Good luck!