one notice about shutdowns, I am using since beginning kubuntu 12.04 and upgrade almost every day, after installing wurkwith.us kernel there have been couple kernel updates from ubuntu.
I did forgot that I have manually set default kernel to reboot 2 and it should been 3.2.0-12-ux31, but last night after dist-upgrading kernel was 3.2.0-14 and it has been gone to default in reboot. not manually installed ux31 version
so my point is I was using 4-5 day ubuntus default kernel without shutdowns !
edit: mainline kernel 3.3rc3 is released this morning