Ok. During server startup (or shutdown for that matter) are there any warnings or errors in the log file? Is there anything in the server logs from around the time this started to occur?
You haven't commented on the contents of the catalogs being accurate or not yet. Assuming they are not (seems likely) I'd say the decision is about how much effort to spend figuring out why they are incorrect versus just restoring from backups (you can/should save the PostgreSQL installation and data once the server is shutdown).
WAL may provide some clues if continued research is needed (in addition to whatever logs or other data you collect) though that is not an area I am practiced in.
