When I migrated my Domino Directory administration server from iSeries to Red Hat users started reporting seemingly random problems with room and resource reservations. Some reservations worked while others didn't. It wasn't a big deal, but it was one of those annoying things people would mention every week or so.
I finally dug into it and what I found was very interesting. In the logs for my server I kept seeing errors about a file RSVP.nsf not being found. I checked and careful scrutinity showed my reservations database is called rsvp.nsf. When I looked at the room and resource documents in the Mail-In Databases section of Domino Administrator some were listed with the database filename RSVP.nsf. I don't know how this happened, there isn't anywhere to enter the filename when you create a new resource. Apparently Linux is case-sensitive with regards to reservations while the iSeries is not. I changed everything to point to rsvp.nsf and it all works now.
One more "gotcha" to add to the list: check all filename references for proper casing after migrating to Linux.