I have 3 identical Dell Vostro 200 slim desktop machines running Vista on the same wifi network. One of the machines has developed an issue where its wifi connection is very slow; webpage loading times are easily a factor of 10 slower than a few weeks ago.
For example: loading thesimpsons.com takes <20s on machines A and B, but machine C still hasn't completed the loading after 2mins.
I've checked the settings for the built-in wifi card and they're again identical.
Viewing the network usage while a browser open shows the download happening, and closing the browser immediately stops any download traffic - so there's nothing on the machine leeching bandwidth.
None of the machines have QoS enabled or even installed.
Vista notes the card as a Broadcom 802.11g Network Adapter "BCM43XG_NT60".
There's no previous driver to roll back, and there are no new drivers from windows update.
What would be the next step to debug this issue?