Odd Time Machine behaviour

[navaira]

Hello,

I googled this problem and I found NO hits whatsoever. But surely I can't be the only person with this problem?

Time Machine informs me that the latest backup has been made at DATE_TIME_FORMAT. That's what it says. Opening preferences tells me latest backup was made at DATE_TIME_FORMAT, and so will be the next. When a new backup is happening, "Cleaning up old backups" works, "Backing up: x GB of y GB" works, then "Cleaning Up..." results in this:

TIME_MACHINE_ERROR
RESULTCODE_999_MESSAGE

What can be causing this? I've been running Yosemite for months without problems, this is new. My backup drive doesn't have much space left but surely that's what cleaning up old backups is for...

System:
GA-Z97N-WIFI
i7-4770s
Crucial Ballistix Sport 2x8GB
EVGA GT 740

Hard drives:
System: Kingston SV300S37A120G
Data: Seagate ST3000GM001
Backup: Hitachi HDE721010SLA330

ANY help will be appreciated!

 

[navaira]

1. Deleted preferences file
2. Changed to a different drive (losing my old backups in the process due to stupidity)
3. Nothing changed.