FWIW, I have never managed to flash VANILLA on any of my 3 N900s. Using two different PCs, both 32 bits, running Debian Squeeze, Debian Wheezy, EasyPeasy (basically Ubuntu 10.04) and Windows XP. Flashing COMBINED worked fine in all cases, but VANILLA failed every time. As a conclusion, I do not believe it can be done and treat all reports of people having done it successfully as myths.