Hi there. This is a know issue with this breed of cards, I just had to resolve the exact same issue myself yesterday. Sometimes my computer would take 12-15 hours to freeze, sometimes it would freeze before startup was even completed, at my login screen. Given long enough you'd notice the system would freeze even if you didn't connect directly to the internet but still left the network connected. It's not actually a problem with the cards, so much as the drivers they came with. Try this before messing around in BIOS or reformatting again.
The later revisions (B, C, etc) of many DWL series cards use Atheros chipsets, so what you need to do is get the latest Atheros drivers that support your model of card and install them. (I am, of course, assuming you have a Rev. B or higher) The newest drivers I'm aware of are Atheros 4.2.2.14, which came out in April of this year.
Now, first thing you do in uninstall the D-link drivers, and the airplus config utility if that's installed, then reboot the system. When the system reboots, it will detect the card and install microsoft's d-link drivers, this is ok. Go to the device manager for your wireless card and manually install the new Atheros drivers. It will give you 4 options of card to choose, select the card model "Atheros AR5006X Wireless Network Adapter".
Once this is done you should be ready and rarin' to go, no further reboots required (but always helpful).
Now, I won't say 100% that this will resolve your problem, because with computers there's always something else that could be wrong. But I hope it helps