Currently Being ModeratedOct 13, 2012 11:33 PM (in response to DanK)
Probably indicative of a Time Machine target disk too small for the task.
How large is your Time Machine disk compared to the sum of the sizes of the disks it is backing up? It should be two or three times as large, maybe more.
Do you have any very large files that change often being backed up (e.g., virtual machine images)? If so, increase that ratio.