Filter button seems not to work with Firfox 1.0. Also, not sure if its related, Firefox JS Console is not very happy with table.js.
Error: TTP1K has no properties
Source File: http://dcuser1.xxx.com:8080/tables/table.js
// Title: Tigra Tables PRO
// URL: http://www.softcomplex.com/products/tigra_tables_pro/
// Version: 2.1
Most probably the error is in the your HTML code, please see carefully where <FORM> tag is.
Give me please URL to your page to be able to help you if need further.