This sounds very similar to the following bug, which also involves rdesktop and gnome-screensaver and includes a workaround:
https://bugs.launchpad.net/ubuntu/+source/gnome-screensaver/+bug/58093 -- mouse issue screensaver + rdesktop https://launchpad.net/bugs/70075 -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
