The only possible issue is that you've run out of usable memory by trying to run too much on the device at once.
Tomtom is a system hog, and needs a lot of free mem - tonnes the more POI sets you have enabled.
Ensure you close as much as possible, and only run the esential POI you actually use all the time. Enable the others to show on the map as and when you need them.
You'll still be able to navigate to them unless you physically remove them
