peled said:Welcome to the club of those hit by the iTunes build in Sync Virus.
It is a known fact , that You never ever put a sign on automatic SYNC on any thing except the Application. Make all the rest Manual.
In you case I am sure you put a sign for automatic sync your photos, but it was pointing to an Empty folder on your PC. That was as if ypu instructed iTunes to delete all photos from you iPAD.
(see my permanent signature down below - It is an educational one)