I'm in the same problem. Every Rom I've tried (mostly by searching for Coby Generation 3 in Google, or though threads like this) they've all had inverted axis problems. I've tried overwriting the driver files I found in some other thread, but the problem is persistent.
Can anyone point us in the right direction? So far I'm just after stock installation, so I can start from scratch. It's not my tablet so it's sitting unused for a few weeks.