I am not able to work with some file format in Microsoft Office 2003 after applying a SP3 patch. The update was fine and there were no error. Before that I use to view lotus file format in Excel. They were wk1, wk3, etc. But after installation of the update I cannot see any of them opening up in Excel. The formats are blocked by Office update. I found a registry tweak that also did not helped much. I had changed that the keys of FileOpenBlock key located under HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\. And another one located under HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Excel\Security. But that did not helped much. The below kb article also did not helped much in fixing the issue.
Information about certain file types that are blocked after you install Office 2003 Service Pack 3