What to do when Time Machine backup is taking forever? Yesterday I bought a 500Gb external USB drive for the sole purpose of backing up my laptop, which has 45Gb of data. After turning on Time Machine, it began the first backup, but after an hour or so reported there was still 4 hours to go. I had to pack up, so I aborted the backup.

This morning I requested Time Machine to do a backup, and now 3 hours later it tells me it has backed up only 156Mb, and there is 42 days to go!?!

I can't believe this is right, so the questions are:

What is going on?
What is the best way to deal with it?
Aborting a backup like that sometimes has unfortunate consequences. If this is your initial backup, consider erasing the backup drive and starting over before you go to sleep. That way, the drive can run overnight without you having to worry about leaving before it's finished. 

Also make sure that the drive is correctly formatted as as HFS+ extended journaled, with a GUID partitioning scheme.