Since Time Machine runs hourly I'll get 23 to 47 backups that work fine, then the error. It's always a single file that seems to blow out the backup and generate the message:
I haven't encountered this on my MacBook Pro yet, only on my Mac Pro. The time machine icon in the menu bar shows this:
I first encountered this problem at the beginning of June and it is definitely a byproduct of the 10.5.3 update. Jeff McCord has documented similar problems on his blog. There seems to be two solutions that work for me:
1) Try again. About half the time just telling Time Machine to try again seems to work.
2) Look at the backup volume. If there is a file on your backup volume that ends in "inProgress" then drag it to the trash can. You'll be prompted to enter your password. Once done try Time Machine again.
I'm getting a lot of hits on this blog from people searching for Time Machine Error so hopefully this abbreviated solution set will help them clear the error until Apple fixes it.
I have read reports of people saying this may be related to using Growl—which I use with several of my applications—though I only seem to be seeing this error consistently on my Mac Pro. Though a relatively minor error that is easily recovered from, often by doing nothing but letting Time Machine try again, I would really like to see it eliminated.