Ripley goes into an all out panic from the doorbell too. Even one on the tv will send him under the bed in the back bedroom. He's been that way his whole 12 years. He's even taught Jazz to run too but she immediately comes back out. He doesn't get quite as upset as Boomer though, poor guy.

Wished I knew something to tell you to help but I don't. Maybe you could go sit with him and reassure him every thing is okay.

Good luck.