I think this has something to do with the file paths in your qgis.bat. Could you post the contents of your qgis.bat? For example, if it looks like the following
@echo off
SET OSGEO4W_ROOT=C:\Program Files\Quantum GIS Lisboa
call "%OSGEO4W_ROOT%"\bin\o4w_env.bat
call "%OSGEO4W_ROOT%"\apps\grass\grass-6.4.2\etc\env.bat
@echo off
path %PATH%;%OSGEO4W_ROOT%\apps\qgis\bin;%OSGEO4W_ROOT%\apps\grass\grass-6.4.2\lib
start "Quantum GIS" /B "%OSGEO4W_ROOT%"\apps\qgis\bin\qgis.exe %*\
You might want change the path in
SET OSGEO4W_ROOT=C:\Program Files\Quantum GIS Lisboa
to its short name version
SET OSGEO4W_ROOT=C:\Progra~1\Quantu~2
or whatever its short name is. Save and then try loading QGIS again. It seems to be having problems with paths that have spaces. I hope that helps.