Time Machine Identity Changed
When Time Machine attempts backup, I get the following message:
The identity of the backup disk has changed since the previous backup.
...accompanied by two options: Use This Disk or Don't Back Up
How could this have happened? How worried should I be about malware? How do I fix it so that I can access my Time Machine backups (I cannot now) and that the back ups continue?
iMac, Mac OS X (10.6.8)