OK. First, I must say that while a good admin, I am not a Linux user and only common components of OSs apply here. You WILL get better advice from a Linux power user.

Thus far, what I can recognize is this: Kernel not syncing means what BSOD is for Windows. Meaning, something crashed either in hardware (bad RAM, failed controllers) or in a driver (in you case, modules that run elevated) and the OS halted all writes to disk to keep it from getting (more) corrupted.

Stack trace seems to be in IEEE80211 (which is the segment responsible for wifi). Since at least once I saw a null being dereferenced, it's likely that something in the wifi has unexpected input. Since you have Joiku module loaded but the stuff uninstalled, I think it's a good bet that the listed module finds itself in an unexpected position, a missing value, function, variable.

You could try to kill the module (if memory serves, lsmod lists, rmmod removes). However, other daemons could insmode it back.

Politely, I'd try to install, reboot and uninstall Joikuspot. A later uninstaller could remove the module. If not, try to rmmod and delete module from disk to make sure it stays dead.

It is, however, entirely possible you could have a hardware issue. You can either reflash or, if you want, install BackupMenu, create an image and then reflash so you can go back on the reflash.

Again I say, limited understanding of Linux inner workings. Other people could guide you better. Though I'm quite sure rmmod and renaming joiku module is safe and undoable.

Have fun.