Sage 300 ERP UI container crash - Disable Field edit control after Input

Hi, I came across an problem in Sage 300 ERP 2014,

I have a Field edit control with finder, for that field on record changed event i'm disabling it.  that means after entering value that control will be disabled.

If i select a value from finder its working fine, but if i enter value from keyboard then UI container crashing. 

did anyone came across this issue? any solution?