Time Machine stuck at "Looking for backup disk" after installing Windows 8 via Boot Camp

I've been backing up via Time Machine to an external USB drive and it's been working fine. I recenty installed Windows 8 via Boot Camp and now TM gets stuck forever at "Looking for backup disk...".

I've tried the following, to no avail:

• Using "Select Disk" in TM preferences to re-select the disk
• Deleting /Library/Preferences/com.apple.TimeMachine.plist
• Running system maintenance via Onyx
• Resetting PRAM
• Formatting the drive and setting it up for TM backups again

The Boot Camp partition is on the same drive as OS X (on a 180GB Intel 330 series SSD). During the Windows installation I re-formatted the partition as NTFS.

If I start OS X in Safe Boot mode, TM backups work. In Safe Boot mode, the NTFS partition isn't loaded so I suspect it has something to do with this. Any ideas would be greatly appreciated.