Are you running any add-ons? Another thought that doesn't solve it but at least might make it easier to work with -- when you have all the Osnaps set the way you like, type OSMODE and record the number somewhere. So next time it turns off your snaps, you can type OSMODE and re-enter that number to get your settings back quickly. It sounds like some macro or macros on your system probably start by setitng OSMODE to zero, would be my guess. Good luck!
Hey you could even program your own button to set your OSMODE back to your favorite settings with one click!
If by some odd chance my nattering was useful -- that's great, glad to help. But if it actually solved your issue, then please mark my solution as accepted