Just thought I'd share a fix for an issue I'm experiencing with the latest Basecamp on Windows. Perhaps this will be of use to others.
Issue: Basecamp 4.5x and later crashes when searching for POIs in Topo 24k West
Fix: Switch to Global Map, then switch back to Topo 24k West
I'm guessing this isn't strictly related to the 24k West maps, but is somehow related to other installed map packages as well (24k West is the only one I own, so I can't test this).