IE9 misbehavior with object array

Question

My JS code works perfectly fine in all browsers except IE.

I am not sure why this is happening, the obeserved behavior is

Ext.Msg.alert(filterIds.length) -> gives 2.

Ext.Msg.alert(Object.prototype.toString.call(filterIds)) -> object Array

Ext.Msg.alert(filterIds) -> prints nothing

Ext.Msg.alert(filterIds.toString()) -> alert box doesn show up, hence I was assuming it is giving error.

This doesn happen the first time I am accesing the variable, afterwards this behavior begins. Is it my mistake ?

Thanks

PS: I am using Ext-js 3.4.

On using debug mode I get message like SCRIPT5011: Can't execute code from a freed script for

Ext.Msg.alert(filterIds.toString())

Also this on local variables. [+] filterIds [0] Object, (Array) [+] [0] "0" String [+] [1] "2" String