excellent now we get it to auto run at start up
go to Menu > Settings and then click Default Applications for LXSession
The window will open and click on Autostart on the left - you should see this

just to the right you will see the +Add button and I have put in the box - start typing here
copy and past the following
/home/zeb/nvidia-start.sh
please change
zeb for the name you use to log in with
and then click the + Add bit
This should then run each time the system starts and hopefully fix your woes whilst we maybe find out the real reason it is happening.
Regards Zeb...