MacBook Pro - Can't use Time Machine

Hi

I'm hoping someone can help with a problem I'm having using TimeMachine on a new Macbook Pro backing up to an external notebook drive via USB.

The backup starts and runs for a while, but whenever I return to it (varies between minutes or hours later), I either see 'Finder cannot quit because a process is in progress' (in this case the backup continues) or the machine is back at the login screen and the backup has stopped or at least is incomplete.

I then log in again, try selecting 'backup now' and the same thing happens.

I've tried watching the machine but haven't caught the precise moment it happens.

The disk's SMART status of both disks is fine and there are no other programs open. I've tried this from the admin user and my main user. The main user has FileVault enabled, but I don't this should make any difference.

The only thing I can think of is that something is making the machine reboot part way through the process.

I set all energy saving preferences such that the machine won't attempt to sleep or shutdown or stop the disks spinning at all, so that isn't it.

Any help appreciated.

Many thanks
Stuart

I would really recommend turning File Vault off. If not:

10.5: How to use Time Machine with FileVault - Mac OS X Hints

File Vault can and will create other issues for you down the road. So many, that I never even tried turning it on after reading about them when I got my first Mac 3 years ago. Can only recommend File Vault for those that keep business related sensitive data on a machine that is carried around with you. I also recommend you maintain a minimum 50% free space on the partition.

Note, that with file vault turned on, Time Machine must back up the entire home folder with any single modification made. You have basically lost the ability of incremental backups.

Better yet, if you must use FV, I'd recommend SuperDuper!.