Suspend does not work on E6420

[bigbug21]

Suspend to disk does not work on a Dell Latitude 6420 with a freshly installed Kubuntu 11.10 64-bit system. The system properly shuts down for hibernation, but it fails to wake up again: While there is some harddisk activity, the screen remains dark and there is no apparent response to keys (e. g. CTRL+F1, CTRL+ALT+DEL, power switch). According to lspci, the laptop has a built-in "nVidia Corporation GF108 [Quadro NVS 4200M] (rev a1)".

However, when I switched to the most recent (proprietary) nvidia drivers with "jockey-kde", hibernation worked. But then, the system goes dark when switching from (a still visble) bootscreen to KDE's login manager while it is on a PR03X Docking Station (I have a VGA cable attached to it). With the screen lid open and undocked I get a picture, but that doesn't take me too far in my office. When I switched back to the previous (open) drivers, resuming from hibernation fails while I get a picture from the docked laptop.

Suspend to RAM, which would do just fine for me, is not presented at all.