no right click past

Hello and good evening.

     I an my users are on 2.6.3  today one of them asked why he cant Right click Past. Very strange as i and other users can.  He is trying to past test from a document into the window.  I told him to use CRTL-C and CTRL-V and that works.

     But still why does right click not work?

     Thoughts?

     Thanks.