Where did my podcasts go?!

I plugged in my ipod nano for the first time in a couple of weeks, and when iTunes loaded - it had NO podcasts in it... Every single one. Disappeared.

The ipod popped up a message saying "can't sync podcasts because there are none to sync with" or something similar... ('fraid I didn't write the message down at the time).

Has anyone else ever had all their pod-casts just disappear? I'm fairly sure they weren't accidentally deleted.

Any way to "retrieve" them without finding out each url and re-subscribing and downloading them all again? I had several hours of unlistened to stuff that will take an age to download again!

I do have a back-up of the iTunes directory on another computer - from a week ago... Any chance I'd be able to retrieve the missing podcasts from there?