Restore an image of your drive?
Don't know if you use System Restore (I don't, since I don't think it's very reliable), but if you do have a restore point before all this, you could try that.
Seriously, our setups are different so I don't know if I have an answer. My TV (Sam HLP-5063) doesn't have firewire, so my PC is connected to the firewire port on my STB (moto 6200). I've only installed from firestb.msi. IIRC, during that setup (or actually after rebooting and with the New Hardward wizard) it asks for the inf file to install the drivers (there was a choice of three, I think). I chose the highest numbered one, thinking it was probably the most current (who knows....). So that would be the file to check out if you want to.
I gather that re-running meistb.inf (not familiar with this; is it for non-MCE machines?) after un-installing firestb.msi doesn't work (?). I can only say again to re-install firestb.msi, un-install the devices from Device Manager, then un-install firestb.msi, reboot, say a little prayer, and start over.
Sorry I can't offer more.