Mine does the same thing! It will often just disappear completely! It is really frustrating when you are trying to do a quest. I've noticed when it disappears, it will reappear behind you.. turn and walk backwards for a few feet, and it should fix itself.
From: Issilidur | #005 Surely you can't use the map or read/listen when a quest is given...
Map sucks, doesn't even show you where you are on it. The trail is meant to be a replacement for the minimap. Terrible way to go about making it 'easier' for people Molyneux. Minimap is srsly one of the best things he could have added.
Phenom II x4 955 3.2GHZ, 4GB DDR3, HD4890 1GB, W7 Ult x64, 22inch LCD Asus monitor. http://imgur.com/CPqGr.jpg ¬_¬