If the "item" field text contains a string which is identical to another field name,
it will prevent VB functions from working properly if they're using that field as a parameter.
(Possibly, the bug could involve any String from any text field, and not just the item field, of course. Haven't tested that though.)
I can reproduce that easily. [ EDIT : but only with the example below...! ]
Seems to be a problem with my own code. But can't find where the problem lies...
Code example used for item color calculation (important lines at the end of function):