I have also found with my tomtom1 v4 that occasionally it will not find satellites until i turn it off and then on again. I dont have to reset. My problem is not as frequent as yours.
Has it always had this problem or is it possible it was actually a Tomtom home update that has caused the problem?
Maybe try setting it back to factory original and see if it still has the problem.
It is hard to say if the issue occured after an auto update from TomTom, as I connect for update weekly.
Have tried resetting to factory specs, but cannot remember why I do not continue with this. Without trying again, it may have been that this action creamed my POI files, screen colours etc.
Did a complete reinstallation of tomtom software in late June. Problem has not surfaced for the past month, so hopefully it was caused by a corrupt file somewhere.