Comment 2 for bug 697210

I am getting the same error, Ubuntu, Lucid 64 bit.

But the indicator still launches despite the error on install.
---
sudo apt-get install indicator-virtualbox
...
Unpacking indicator-virtualbox (from .../indicator-virtualbox_1.1.1~astrapi~lucid1_amd64.deb) ...
Processing triggers for desktop-file-utils ...
Processing triggers for python-gmenu ...
Rebuilding /usr/share/applications/desktop.en_US.utf8.cache...
Processing triggers for python-support ...
Setting up indicator-virtualbox (1.1.1~astrapi~lucid1) ...
gtk-update-icon-cache: No theme index file.
gtk-update-icon-cache: No theme index file.
dpkg: error processing indicator-virtualbox (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 indicator-virtualbox
E: Sub-process /usr/bin/dpkg returned an error code (1)