NIS 2013 - Tried to reinstall itself on sytem restart

I installed 2013 2 weeks ago , but today NIS needed a restart to apply new virus definitions , and when my system restarted i found on my desktop the NIS Download manager and Installation files , and then NIS tried to install itself again , even though my NIS 2013 is working fine . I Cancelled the reinstallment anyway .

 

Any ideas why this has happened ??

 

edit - I restarted my system again - then NIS decided to reactivate itself and now it seems ok .   Anyone else encountered this ??

 

 

Windows 7 - 64 bit