I don't mean to scare you but there was a security vulnerability within the printing service in Linux a while back. The vulnerability was patched, but just in case I would enable the firewall to be extra sure nothing weird is going on. You can find instructions in my post over there in that thread.
Back to the issue at hand, it's possible that a recent update has messed with your configuration somehow. You may try to rollback the kernel version to a previous one, and see if that helps. Checkout this guide on how to enable kernel selection at boot: