powerpoint association within Lotus Notes 6

Hi, I’m hoping someone can assist with this issue. I have a user who is unable to launch/open a powerpoint attachment within notes. He can detach and view it fine, but the option to launch/open fromnotes comes up with an error message ‘cannot find associated program to open file’. I have reinstalled notes and office….other office attachments ie. word and excel can open withot a problem.
Any advice on this??