Hmmm... that'll keep us TSOP-flashers on our toes, no more running on autopilot when modding a box!
Unless, of course, there's something else it's grumbling about, such as extra data in the EEPROM (

), a completely rearranged EEPROM (

) or a bigger EEPROM (

).
It'd be worth trying the new BIOS on 1.2/1.3 (Conexant) and 1.4/1.5 (Focus) machines, as these ought to be more closely related to the 1.6 machine. Unfortunately mine's a 1.1, so I can't help (and I've just dropped a Xenium in it too - bugger!)
Bourke, any chance of you passing an EEPROM dump onto the appropriate crew? 007savewithevox should let you do it (just make sure there's a "backup" command in your evox.ini). Perhaps they'll spot something odd in there.