Win XPHome, Pentium 2.4. 1gb ram. Nv 5600xt Have lost all sound in Flight Simulator ( fs9 and 2002). It crashed whilst in flight! Have re-installed both versions. All settings in sound manager and in FS ok. Can access all aircraft etc sounds from aircraft/sound folders and play ok. Can also play ' my music'. All drivers are ok. Although probably not connected, my fps have gone right down. Tried to run benchmark on graphics card, but wouldn't run as it couldn't find 'DSOUND.dll. Re-installing DSOUND may solve the problem'. Is this missing file likely to be the cause in FS? Have downloaded it and it says extract to 'System Registry' location of which I can't find. When I manage to open the zip all it has in it is 'MXO'. Any help has to be in simple terms for a simple mind. Thanks.