Wireless drivers need to be reinstalled after rebooting

I've been using Vista Ultimate for two months now, on a wireless network. My
computer connects through a Belkin 802.11g wireless card. However, in the
past few days, every time I reboot the computer, the wireless connection
stops working. The card stops showing up in device manager, and I need to
reinstall the drivers from the CD in order to get it working again. To my
knowledge, nothing about my computer set-up has changed, and I have run
various virus and malware scans, all of which have given my computer a clean
bill of health. Does anyone have any ideas what could cause this? It's
getting rather annoying, as the drivers can only be installed on a reboot, so
I basically need to turn on my computer twice every time.