I add the hotspot the regular way.

Yet it doesn't show up as available when I try to connect to it using my other Ubuntu laptop. And nothing can connect to it. Yesterday, I successfully made it work for 5 minutes and then it stopped without me changing any configuration.

I've already tryed resetting the DNS.

Edit: I've updated my Broadcom 802.11b/g driver to a generic but more recent version.

I've also repaired the WMI, now the advanced tab of my primary connection is available and the hand meaning the connection is shared appeared. But the computers still connect the wrong way around. (Windows to ubuntu instead of ubuntu to windows)

Reinstalled SP3...