A colleague of mine posted this the other day. We haven't got any nibbles yet and I wanted to elaborate on the issue.
We are having trouble running the r.mapcalculator function and receive the error below

I have gone into the file "HistoryDialog.py" and changed a reference to Sextante on line 101 to 'sextante' (original text shown below). I think I am clutching at straws here, because after this change I receive another error altogether.

A good googling returned nothing related to the 'sextante is not defined error'. Surely someone else has come across this before. Also for us it is happening on Ubuntu and Windows. We installed the latest dev version through Osgeo4w installer but no luck!!