I installed Ironhide (aka BumbleBee). It couldn't get it to work, but now I can't uninstall the package and it's preventing me from installing or removing anything else. Any ideas what I can do to fix this problem?

$ sudo apt-get remove -f ironhide

Reading package lists... Done

Building dependency tree       

Reading state information... Done

The following packages were automatically installed and are no longer required:

  virtualgl acpi-call-dkms virtualgl-libs easybashgui

Use 'apt-get autoremove' to remove them.

The following packages will be REMOVED

  ironhide

0 upgraded, 0 newly installed, 1 to remove and 65 not upgraded.

1 not fully installed or removed.

After this operation, 1,901 kB disk space will be freed.

Do you want to continue [Y/n]? Y

(Reading database ... 297969 files and directories currently installed.)

Removing ironhide ...

groupdel: group 'ironhide' does not exist

dpkg: error processing ironhide (--remove):

 subprocess installed post-removal script returned error exit status 6

Processing triggers for ureadahead ...

Errors were encountered while processing:

 ironhide

E: Sub-process /usr/bin/dpkg returned an error code (1)