1st: update to Linux,no the other way to do it in win7 644
2st: In Win7 64: use 32bit questasim 10.2c +pc version Debussy(Debussy 5.4v9)
for exemple,if your project file which name is a.mpf(questasim/modelsim project file)
in a.mpf add a line as bellow:
Veriuser = e:\novas\debussy\share\pli\modelsim_pli54\winnt\novas.dll
e:\novas\debussy is your debussy install dir.Run 32bit questasim 10.2c ,Not 64bit questaim 10.2c