I think that it was the typical problem for MK3.... Check the Mode of navi SW image - it should be Mode2 for MK3... otherwise navi really would crash....

Try to do the following:
1. Find navi SW which was created in Mode2 or create it using Mode2CDMaker, burn it on the slowest speed, make the error check
2. Make the reset of your navi (as I discribed in my previous post)
3. Make the downgrade on v17. Oe more time, it could take several minutes till navi starts updating.
4. Make the update with new Mode2 software.

No sence to use v32 because for MK3 starting from v21.1 soft is the same SW3-1/63 and if this soft is already in the navi it will not upgrade.....