USB Adapter Causes Freeze

Now I did mention in an earlier post the issues with upgrading to Ubuntu 12.04, all the hassle and pain with reinstalling the system. I was really hoping that a fresh install would solve all my problems and I can have a fresh, clean start. Turns out it's not that simple.

Problem description

Soon after my reinstall I have discovered yet another issue, namely a system freeze occurring when I plug or unplug my external, USB wifi card. This SL1504N (Realtek 8191S chipset) card was perfectly working in the previous version and it is working on Windows as well. The weird thing is, its not working only in 50% of the time. So basically its a lottery whether or not after a restart I get to use my card. If it doesn't work and I try to unplug it my system crashes, kernel warnings appear and there's nothing to be done the system is dead, this is followed by a rough power-off.
I don't know if this issue is in connection with another error message that I seem to get occasionally with nautilus, but even after reinstalling nautilus in the synaptic package manager both the freeze and error messages remained there.


Also, this might be linked to the USB card problem explained above, I am having shutdown hungs as well. The dots start to move, but that's about it, nothing happens.


I am quite disappointed at this point since instead of enjoying and using the new version of Ubuntu for other more productive tasks, I'm still stuck fixing the many errors of the upgrade.

I have tried reinstalling nautilus from the Synaptic package manager and fixing broken installs with:

sudo apt-get install -f

command, but they didn't work and I still get the system freeze or I'm simply stuck without my network card that I want to use.

Temporary fix

Now my wifi card is not detected from time to time. Today (after not using my Ubuntu for a while because of the above mentioned issues) I have discovered that if my system doesn't recognise the USB adapter then I shouldn't try to unplug it and plug it back in, because it will freeze as soon as I remove it. Instead what needs to be done is that the wifi should be switched of  on the hardware (On my HP laptop there is a swipe button to do this, I guess most of the laptops have something like this) and then I can unplug, re-plug, activate the hardware with the button and it will work (or it did today at least).

Unresolved

Shutdown hungs remain still an issue. Even after downloading 160 Mb of updates today it was still there and had to force shutdown. This issue will need some deeper investigation.