Open with . . . no longer allows me to choose any of my portable apps

I recently have been unable to open documents using the 'open with ...' in the context menu of Windows (XP) and searching to my portable apps (eg pdf with Sumatra). I have not done anything different. This behavior occurs on both my work machine and my home one (where I have administrator rights). It seems to have coincided with the recent windows patches from Microsoft, but I do not know if there is a connection. The only workaround I have for the moment is to open the application first and then open the document through its navigation (eg start OpenOffice Spreadsheet and within it open the .ods file.) Has anyone else experienced this recently?