Fatal error: Using $this when not in object context...

[stud]

When attempting to edit another users post, i am getting the following error:

Fatal error: Using $this when not in object context in /home/****/forum/editpost.php on line 433

What's funny is that no modifications were done to the editpost.php file.. and when I attempt to edit any members post - using the AJAX 'quick edit' system - this error occurs.

However when I attempt to edit any of my own posts, it does not occur. Very odd problem indeed that I am still struggling to trace the source of.

The only 2 mods installed on my boards at all are CMPS and vbArcade - neither of which should technically interact with the forums and editpost.php file whatsoever!

At first, I suspected some incompatibility of the AJAX system - but it occurs even with AJAX disabled.

Steps taken:

a. I shut off the AJAX 'quick edit' feature - and this problem still occured.
b. I disabled every single plugin one by one, still happened after each.
c. I can still edit my own posts fine... this problem only occurs when an Admin attempts to edit another user's post. This has been confirmed by another admin on the forums.
d. Replaced the editpost.php file - still occurs.