Did you try building the drivers as instructed in: http://www.linuxtv.org/wiki/index.php/Hauppauge_WinTV-HVR-1800
Look at your kernel messages. You should see some messages related to loading the v4l2 drivers.
and look for messages related to cx23885 (this is the driver that the card uses) or other error messages.
I have the same Hauppauge 1850 card and also getting errors when the drivers are loading.
The kernel we are using (2.6.27-17-generic) should support the drivers out of the box. After getting errors, I tried adding the prebuilt drivers and also building the drivers from source - all trials without success (see: http://forum.linuxmce.org/index.php?topic=10649.0