I lost my Power Point file association

I am trying to open a PPS file as I have done in the past. For that I click on open and then it says it is going to open powerpoint slide show, but I get an error that says "C:=Documents and Settings=Compaq_owner\local settings\temporary internet Files\Content/IE5\R7WV57YX\ChristtheRedeemerinRio.pps is not a valid Win32 application." I went in Explorer and checked file type and the PPS extension is associated with the powerpoint program. I also checked to change it to the correct program but still clicking on the PPS attachment gives the error. I have saved tge file to the HD and then did a double left click and I get the same error. But when I do a right click and tell it to open with Powerpoint the file will open and run properly. So, why I cant open my PPS file by clicking on it as in the past? Thanks

You can try to re-register Powerpoint. First quite powerpoint if it is running, and then choose Start and then Run and then type the full path to your Powerpoint.EXE file surrounded by quote marks, followed by /regserver -- it will look like "C:\Program Files\Microsoft Office\Office\Powerpnt.exe" /regserver. After that powerpoint will start and re-register itself, including resetting the proper file associations.

I think that there might be some issues with Adobe Reader so you can try to use some different programs such as Foxit Software.