Well two days ago someone told me, that if he puts my map onto his GPS it's not booting anymore (or bootlooping after trying to load maps).

The really strange thing is, I cannot find out at all why this happens. If I only transfer half of the map, it is not bootlooping, if I transfer the other half, not bootlooping. If I transfer both halves as separate gmapsupp.img files, still okay. However if I transfer the map as one full gmapsupp.img - then neither Oregon 550 (newest beta firmware) nor etrex 30 (several firmwares tried) doesn't start anymore.
It does not matter if I create the gmapsupp.img with Mapsource, Mapinstall/Basecamp or mkgmap. It does not matter if I create --index with mkgmap on sending it.
And it's not about the integrated contourlines (7*.img) -- exclude them, same problem.

So here is the file for testing (do not install it on internal memory, else your GPS device may be ready for  sending it in to Garmin).
ftp://ftp5.gwdg.de/pub/misc/openstreetmap/openmtbmap/mtbfrance_broke.exe
(note simply unpack this installer with 7zip-full on Linux - its lzma packed).

Note, old GPS devices like Vista HCx cope fine with this map.

I more or less give up trying to find the fault. However as this is the first time since a very long time, mkgmap created maps can potentially break a Garmin GPS - I post it to the list without knowing a way to figure the problem out.
It has nothing to do with my style either I would suppose, only map for me where this happens.