Running Photo Gallery on more than one PC

I recently migrated to Photo Gallery (PG) . On my desktop PC I've tagged, captioned, corrected dates, flagged 'problem images' for all of my pictures. I then copied my entire My Pictures folder from my desktop PC to my laptop. When I open PG on my laptop many/most of the images have lost their corrected dates and captions. The tags all seem to be there, but all flags have disappeared. What gives? Is there an index file buried in the PG application that needs to be copied over? Would really appreciate some help on this....thanks!