Not enough quota is available to process this command

This unhelpful message appeared on my computer today when moving some files.

I run Active Directory and Roaming Profiles so my first thought was if I’d set a user disk quota, however, this wasn’t the case.
A quick search pointed me in the direction of:
Control Panel, Sync Center, Offline Files, Manage Offline Files (left-hand side), Disk Usage tab, Change Limits
(Windows 7 64bit)
Once I’d increase the disk usage all was well again.
Now Why didn’t they put the words ‘Offline Files’ in the error message or perhaps even a link?