Power locks began acting up. Went from working perfectly to the present condition: From either power lock control switch, passenger or driver, the system will lock any or all front or back seat locks from the open position to closed, but will open only the drivers lock. All others need to be manually opened. Both power lock fuses have been checked and are ok. The change happened in a heartbeat.

Any suggestions as to what might be responsible for this?

Manually opening my locks..... David MacLean