It seems that ExtJS and OpenLayers does not blend well together. One of the bug biters that hit me was the way ExtJS was handling arrays. It would be wise for OpenLayers to be agnostic of these frameworks.

for( var i in blocks ) should be transformed to for( var i = ; i < blocks.length; i++)

I believe OpenLayers Ticket#1362 closely resembles this bug. Thanks to pgiraud for pointing me to the right direction.