I hope that you guys need to talk to your local admin based on the below PDN article. Looks to me that this plugin is not installed properly due to some privilege issues. Please check the below article.
Thanks Ravi- we followed the article, installed the PRPC plug in with Admin help, restarted the system and the server. Also confirmed all registry are in place for MS silver light, still Its not working in IE but its not prompting for plug in to install from OOTB.
For Chrome - There is no option to save Pega prompted plug in, it will take to external web site and Admin can not help on this because its against the firm policy to download something from external site.
We raised an SR for V 7.1.9 and we got some registry setting from GCS and it worked but now the same issue with V 7.1.7