My laptop keeps freezing, why?

Question

The computer is an HP Compaq 6715b .

Whenever I log into Ubuntu, the user interface freezes after around 5 seconds.
Though the mouse seems to work. I have tried to open the terminal using the keyboard. But it seems to stop working when it locks up. I can only get the laptop working using Failsafe graphics mode. (I have tried multiple desktop environments).
The laptop has an AMD graphics card, and a Broadcom wireless LAN card, if that information is neccesary.
At the moment, I run in failsafe mode, using this command:

kwin& plasma-desktop& conky& skype&

None of the other questions and answers I looked through (around 10 of them) seems to be working.

dmesg returns: http://pastebin.com/nQt7rEdg

Answer 1

These lines from your dmesg look suspicious, if I see a --[ cut here ]-- in a log it's usually something important, as is the distinctive-looking call trace that follows:

[   42.752749] ------------[ cut here ]------------
[   42.752792] WARNING: CPU: 0 PID: 493 at
/build/buildd/linux-3.16.0/net/wireless/sme.c:791 cfg80211_roamed+0x91/0xa0 [cfg80211]()

Also note the many cfg80211 errors following. As the "wireless" above suggests the cfg80211 is related to the wireless radio adapter. Is your "Broadcom wireless LAN card" easily removable? Calling it a card suggests you could unplug it easily, if so try that & see if it still freezes/crashes.

If that's the problem, then I don't know offhand how to get that wlan card to work with Ubuntu, searching may reveal some solutions.

Could turn off the wireless's physical switch (if there is one) or unplug it, or...

Here are method that should blacklist a module from being used/loaded, in your case using the "wireless" module cfg80211, (but first take a look at lsmod | less and make sure there's a "cfg80211" module, it's in your dmesg log but just in case, or for anyone else who's not you) .

• Create a /etc/modprobe.d/blacklist.conf (if non already existing) file and add the line:
  blacklist cfg80211
  (or whatever the exact module name is. https://askubuntu.com/a/110343).
  Then reboot.

  And "Sometimes it is needed to update the drivers cache after editing the blacklist.conf file. To do this, run:
  sudo update-initramfs -u
  ( https://help.ubuntu.com/community/Loadable_Modules#Blacklisting_Modules )

• Or try booting with the kernel parameter (in grub in the "linux" line)
  modulename.blacklist=yes

  Or in your case:
  cfg80211.blacklist=yes

  (may not work with all modules... https://askubuntu.com/a/110349 )