This is a known problem, caused by a Microsoft office update. 2016 SP4 no longer has the issue, if you can't update to that SP, you will need to turn automatic updates off.
Dear Richard Bremmer,
Thank you for your reply.
Actually we are using 2015 SP4. in N number of machines,but this problem comes only in 2 machines.
I think the permanent solution is, only to Re-install the solidworks on those machines.