My local map seems to be almost completely shot. Interior cells work fine, but exterior cells behave erratically. When starting a new game or loading a save, the first exterior cell I set foot in works fine, but others seem to be displayed in the local map at random, even if they were displayed properly just a couple minutes ago. The world map, on the other hand, works perfectly.

I am using the Morrowind Code Patch v2.0 and Windows XP SP3. The Map Expansion and Fog of War Fix are both enabled. Toggling them in any combination does not fix the issue.

Does anybody have any ideas?

Known issue, I don't believe there is a fix though.

Do you have a high-res replacement of land_default.tga installed? If so, rename it to something the game can't load (such as land_default.old), then try starting a new game. One of the two maps (I forget which) cannot handle higher-resolution versions of the land_default texture, causing the pointer to get stuck.

I do not have a land_default.tga replacement.