I am unable to use GRASS algorithms in QGIS 2.0.1 (on windows xp). I've already configured the GRASS path. The algorithms seems to work correctly (I cannot see errors in the log), however in the end the following windows appears:
Oooops! The following output layers could not be open Output layer: C:\DOCUME~1\MCORDI~1\IMPOST~1\Temp\processing\ebc399ac72364b68aad151d232a1379a\output.shp The above files could not be opened, which probably indicates that they were not correctly produced by the executed algorithm. [...] It seems that GRASS is not correctly installed and configured in your system. Please install it before running GRASS algorithms.
Here below the log for the v.distance command
Algorithm v.distance - Finds the nearest element in vector map 'to' for elements in vector map 'from'. started g.proj -c proj4="+proj=utm +zone=32 +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs" v.in.ogr min_area=0.0001 snap=-1 dsn="E:/Tavolo Tecnico AUSL-Pr/GIS" layer=asma_DOM_select output=tmp13811305945511 --overwrite -o v.in.ogr min_area=0.0001 snap=-1 dsn="E:/GIS DataBase" layer=eurostreets_EmiliaRomagna_FRC04 output=tmp13811305945512 --overwrite -o g.region n=4999266.578 s=4848836.96069 e=801201.169359 w=516043.246024 res=1 v.distance from=tmp13811305945511 to=tmp13811305945512 upload=cat column=mindist output=output6f83c8f8869a4a41bdbc595d37c12891 --overwrite v.out.ogr -e input=output6f83c8f8869a4a41bdbc595d37c12891 dsn="C:\DOCUME~1\MCORDI~1\IMPOST~1\Temp\processing\ebc399ac72364b68aad151d232a1379a" format=ESRI_Shapefile olayer=output type=auto
E:\PROGRA~1\QGISDU~1\bin>set HOME=C:\Documents and Settings\mcordioli
E:\PROGRA~1\QGISDU~1\bin>set GISRC=C:\Documents and Settings\mcordioli.qgis2\processing\processing.gisrc
E:\PROGRA~1\QGISDU~1\bin>set GRASS_SH=E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\bin\sh.exe
E:\PROGRA~1\QGISDU~1\bin>set PATH=E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\bin;E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\lib;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\bin;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\apps\Python27\Scripts;E:\PROGRA~1\QGISDU~1\apps\qgis\bin;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\lib
E:\PROGRA~1\QGISDU~1\bin>set WINGISBASE=E:\Programmi Lavoro\GRASS GIS 6.4.3
E:\PROGRA~1\QGISDU~1\bin>set GISBASE=E:\Programmi Lavoro\GRASS GIS 6.4.3
E:\PROGRA~1\QGISDU~1\bin>set GRASS_PROJSHARE=E:\Programmi Lavoro\GRASS GIS 6.4.3\share\proj
E:\PROGRA~1\QGISDU~1\bin>set GRASS_MESSAGE_FORMAT=gui
E:\PROGRA~1\QGISDU~1\bin>if "" == "" set PATH=E:\Programmi Lavoro\GRASS GIS 6.4.3\bin;E:\Programmi Lavoro\GRASS GIS 6.4.3\lib;E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\bin;E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\lib;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\bin;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\apps\Python27\Scripts;E:\PROGRA~1\QGISDU~1\apps\qgis\bin;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\lib
E:\PROGRA~1\QGISDU~1\bin>if not "" == "" set PATH=E:\Programmi Lavoro\GRASS GIS 6.4.3\bin;E:\Programmi Lavoro\GRASS GIS 6.4.3\lib;;E:\Programmi Lavoro\GRASS GIS 6.4.3\bin;E:\Programmi Lavoro\GRASS GIS 6.4.3\lib;E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\bin;E:\Programmi Lavoro\Quantum GIS Lisboa\apps\msys\lib;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\bin;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;E:\PROGRA~1\QGISDU~1\apps\msys\bin;E:\PROGRA~1\QGISDU~1\apps\Python27\Scripts;E:\PROGRA~1\QGISDU~1\apps\qgis\bin;E:\PROGRA~1\QGISDU~1\apps\grass\grass-6.4.3\lib
E:\PROGRA~1\QGISDU~1\bin>set GRASS_VERSION=6.4.0
E:\PROGRA~1\QGISDU~1\bin>if not "" == "" goto langset
E:\PROGRA~1\QGISDU~1\bin>FOR /F "usebackq delims==" %i IN (
"E:\Programmi Lavoro\GRASS GIS 6.4.3\etc\winlocale"
) DO @set LANG=%iE:\PROGRA~1\QGISDU~1\bin>set PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.PY
E:\PROGRA~1\QGISDU~1\bin>set PYTHONPATH=;E:\Programmi Lavoro\GRASS GIS 6.4.3\etc\python;E:\Programmi Lavoro\GRASS GIS 6.4.3\etc\wxpython\n
E:\PROGRA~1\QGISDU~1\bin>g.gisenv.exe set="MAPSET=PERMANENT"
E:\PROGRA~1\QGISDU~1\bin>g.gisenv.exe set="LOCATION=temp_location"
E:\PROGRA~1\QGISDU~1\bin>g.gisenv.exe set="LOCATION_NAME=temp_location"
E:\PROGRA~1\QGISDU~1\bin>g.gisenv.exe set="GISDBASE=C:\DOCUME~1\MCORDI~1\IMPOST~1\Temp\processing\grassdata"
E:\PROGRA~1\QGISDU~1\bin>g.gisenv.exe set="GRASS_GUI=text"
E:\PROGRA~1\QGISDU~1\bin>g.proj -c proj4="+proj=utm +zone=32 +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs"
E:\PROGRA~1\QGISDU~1\bin>v.in.ogr min_area=0.0001 snap=-1 dsn="E:/Tavolo Tecnico AUSL-Pr/GIS" layer=asma_DOM_select output=tmp13811305945511 --overwrite -o
E:\PROGRA~1\QGISDU~1\bin>v.in.ogr min_area=0.0001 snap=-1 dsn="E:/GIS DataBase" layer=eurostreets_EmiliaRomagna_FRC04 output=tmp13811305945512 --overwrite -o
E:\PROGRA~1\QGISDU~1\bin>g.region n=4999266.578 s=4848836.96069 e=801201.169359 w=516043.246024 res=1
E:\PROGRA~1\QGISDU~1\bin>v.distance from=tmp13811305945511 to=tmp13811305945512 upload=cat column=mindist output=output6f83c8f8869a4a41bdbc595d37c12891 --overwrite
E:\PROGRA~1\QGISDU~1\bin>v.out.ogr -e input=output6f83c8f8869a4a41bdbc595d37c12891 dsn="C:\DOCUME~1\MCORDI~1\IMPOST~1\Temp\processing\ebc399ac72364b68aad151d232a1379a" format=ESRI_Shapefile olayer=output type=auto
E:\PROGRA~1\QGISDU~1\bin>exit Converting outputs Loading resulting layers Algorithm v.distance - Finds the nearest element in vector map 'to' for elements in vector map 'from'. finished