First off, that's an awesome site you got there. really a gtab bible!
That's the exact instructions i followed while flashing ICS...i've been following your blog since i got my gtab...i installed flashback immediately after unboxing, following your site only.
However, even re-flashing the ROM a dozen times now hasn't fixed the issue. i faced the same issue with the previous version of ICS too. have even trying the long NVFlash method.
Another thing that i'm curious about: you're supposed to do cache and dalvik wipe, however every time and with every rom (HC or ICS), when i select the dalvik wipe, i get the error "E:\ volume path not found" or something of this order. Is this normal? and if the path wasn't found, then what's the point of doing the dalvik wipe? To clarify, I don't use an external SD card.
There are errors about the SD ext that are normal. But if the error is about the dalvic cache being on the EXTERNAL sdcard then you have a problem. Did you follow the NEW guide that I wrote a few days ago? It sounds like you need to partition the internal SD.