Cannot save documents: Why might the save be in a loop?

Hi,

Using Modx2.2.2

A client of mine is unable to save any changes in the Manager and i'm stumped as to why this is happening.
I can log in with their details and have no issue saving document changes.
This is happening with any simple changes to documents and they are using Chrome (i've tested in Chrome and it's fine) and apparently the save just loops without ever saving.

Anyone any ideas what could be causing this?

Thanks for any help

J