I don't think this a virus/spyware related problem so you might get more help in either the "Computer Help" forum or the help forum for whatever your operating system is. For some reason you have lost the "open" portion of those 2 files associations but you have not lost the "show" portion of them. You might be able to recreate them through folder options/file types but for specific instructions you would be better off asking in one of the computer help forums like I mentioned above. I had the same problem when I went from Power Point Viewer 1997 version to the 2003 version for the .pps extension and that is how I corrected it but I don't remember offhand exactly how to do it.
When I receive an email with an attachment that contains a WMA, PPS, etc., I try to open it and nothing happens. If I save it to an intermediate folder it downloads and then I go to that folder, I can open the file or application. I have had no problem in the past being opten to open these attachments. This has just started recently and I'm not sure why.