On startup, rdesktop causes the following error message to be appended to ~/.xsession-errors: Gtk-Message: Failed to load module "pk-gtk-module"
Similar errors are reported on bugs 699279, 643129, and 596072.
I'd say this is not rdestkop-related and thus a duplicate of bug #643129. Marking as such.
*** This bug has been marked as a duplicate of bug 643129 ***