Hi Scott,

In ur example use xtype:combo instead of new Ext.form.ComboBox'.
and do reconfigure grid with modified column model(just change the header name). In reload button add code for reconfigure and load the data again.
After modifying ur code follow the given below steps to reproduce
1. After page load freshly click on reload button. so that it reconfigure the grid with updated header name.
2. click on combox editor. It will show data in drop down
3. click on reload button again and then click on combo box editor.

This is happening because of xype:combo.
Please help me how to solve this issue.