It's a Fujitsu Siemens Amilo A1650 (MS2174) with built-in Broadcom 802.11g wireless. It's a few years old now and originally came with XP until I installed a new HDD and dual booted with 7 and XP. It took me a while to track down suitable drivers
(the ATi 200 xpress video driver
was a nightmare and is a custom build) and I expect the Broadcom is probably a Vista driver at best (ver 5.30.21). The wireless is always enabled by default and the driver seems to work fine without issue. Could the driver cause this particular problem...?