If I right click on a pdf file and select Open with and then choose C:\Program Files (x86)\Adobe\Reader 10.0\Reader\AcroRd32.exe when I go back the program does not appear in the list.
I have tried going to Edit/Preferences/General/Set Default pdf handler and then restarting the PC.
I have tried uninstalling ReaderX and re-installing it and then setting the default pdf hansdler all to no avail.