My 2007 Versa CVT will suddenly lose speedometer function (shows zero mph) and RPM's have to increase to maintain speed. This happens every mile or two. Oddly, I can immediately restart the car and everything runs fine until it repeats,...again. Restarting it ALWAYS resets the problem. I replaced the obvious, the fuel pump and speed sensor. While these things needed to be replaced, and made it run far better, there was no change in the initial problem. Any ideas on what it may be, or has anyone else run into the problem?