Just to save someone else my pain...
May main computer is a windows machine, running a linux virtual machine for OE compilation etc. An older linux computer, too slow for compiling, formats SD cards.
Anyway, the point is my serial console is on windows. I've been using TeraTerm 2.3, an otherwise decent little program, but I discovered today that it's Kermit transfer is broken - sending x-load or u-boot for flashing will leave you with a board that can no longer self boot. The windows default HyperTerminal does work, however (as does loading the files from SD card.)