this version without bugs

alien.cpp

@@ -33,10 +33,11 @@ bool Alien::RecreatePath()
 	PathIndex = 1;
 	start.setX(qRound(position.x()/(float)game->cellsize));
 	start.setY(qRound(position.y()/(float)game->cellsize));
+	if (game->Cells[start.x()][start.y()] < 0) return false;
 	srcPath = InvWaveTrace(game->finish,WaveTrace(start,game->finish));
 	for (int i=0; i<srcPath.size();i++)
 	{
-		game->Cells[srcPath.at(i).x()][srcPath.at(i).y()] = 1;
+		game->Cells[srcPath.at(i).x()][srcPath.at(i).y()] = 5;
 		tmpPath.push_back(QPointF(srcPath.at(i)));
 	}
 	srcPath.clear();