Hu there'
Im a LW 9.6 user too, with 6 GB ram. I've experienced these issues too .
3DC is a very resource intensive program. It will chew up your 8 GB ram in no time, with many of its features.
There's a little info at the bottom showing you memory used as you work. However very little warning from your system of upcoming crash/ limits,
or export limits. Notice that even when you "undo" an operation, it stays eating up precious memory fast.
Get at least 24GB ram- as the error says- "Out of memory"
...
On a separate note, why do polys or UVs flip or become absent between the 2 programs?
Rida2