Turning off apport error messages actually does not require installing anything. A slight edit to a system file will do it.
See http://www.webupd8.org/2012/06/how-t...tem-error.html
Apport was disabled by default on older Ubuntu releases. Since 12.04, curiously, it is enabled by default. As a result, now you see the error messages and one thinks Ubuntu 12.04 is a lot less stable than its predecessors.

The "locking" issue is a different thing, and there, you should really confirm whether you also experience these lockups with an older kernel. As far as I can tell, making a choice from the grub menu only allows you to change kernels for the current session. To use an older kernel more permanently, I locked the 3.5.0-24 kernel packages using synaptic, then uninstalled the more recent ones (if someone knows a better procedure to permanently boot with an older kernel, let me know).