Fixing NS_ERROR_XPC_JS_THREW_STRING

In htmls using ExtJs, most of the times I encountered this error in firebug:

"Exception: The request to read the property 
HTMLDivElement.nodeType was denied, when calling method:
[nsIDOMEventListener::handleEvent]" nsresult: "0x8057001e 
(NS_ERROR_XPC_JS_THREW_STRING)" location: "<unknown>" 
data: no]"

After searching a long time, here's what i found on how to fix it:
One of them saying it will be fixed by adding autocomplete="off" to all text fields.
I tried this however it doesn't really work!

And after I look at this ExtJs forum thread, I tried adding this trackMouseOver:false on my ExtJs grid.
And so far I did not have that error anymore :)
Yay!

ExtJs messagebox sample