TimeMachine won't recognize old backups
Hi,
I have a TimeMachine drive running for years over USB. Yesterday I connected it to my AirPort Extreme and ran TimeMachine by accident. Now when plugging the drive back to USB, TM will let me browse all the old backups, but when I try to perform a new backup it acts as if it's the first time I'm running it — meaning it indexes everything and try to store a full copy of my files (which it can't since the drive is full with the old backups).
Any ideas what might have happened when I ran TM over the network and moved back to USB?
Is there any way to force TimeMachine to use the old backups?
It's really cryptic how I can browse the backed up files but not make a new backup.
Thanks in advance.
MacBook Pro, Mac OS X (10.7.4)