I originally had this problem last year, which led to <https://bugzilla.kernel.org/show_bug.cgi?id=37462>. There's a similar independent report at <https://bugzilla.kernel.org/show_bug.cgi?id=37082>. Due to that and other problems I stopped using that HP Mini, but I think I did try the patch available in the above reports and found that it fixed the AR9285 lockups, and I understood that this should have been merged before 3.1 was released. Now I want to use the Mini again and bring it up to date, but I'm experiencing the same problem with kernel 3.2 in Debian unstable, and with Ubuntu Precise beta 2 Live CD. Interestingly, Windows XP suffers similar symptoms, but I know this can be fixed with software, because downgrading to kernel 2.6.32 from Debian stable still cures it. Unfortunately that's too old for a properly working desktop with Debian unstable/testing due to NVidia issues. I've opened a new bug because I can't change the status of 37462.
I tested commit d4930086bdd0c08a8b3a4d66a9c702297cb74a99 and it's hanging with that version too now. Did something change between earlier patches I tested successfully and the committed version? Or perhaps something on the card has "broken" or degraded. I think I'll have to disable the onboard wifi and, if I can't replace it (apparently HP lock the BIOS to that model, but there may be a replacement BIOS to fix it), use a dongle.