It says...
"Under Windows NT, Windows 2000 and Windows XP it is better not to use the legacy drivers that come with your sound card. I strongly recommend you download VDMSound. It is free, can be installed with a single click and seems to work with all DOS games and all sound cards. If you use VDMSound then you need to add one more command to the above procedure:
E:
cd
dosdrv
install
and you need to provide slightly different sound card settings during installation:
Soundcard: SoundBlaster
Port: 220
DMA: 1
IRQ: 7
When first using VDMSound, you may find a "hints" box pops up. You must disable that before running Glidos, otherwise it will pop up behind the Glidos window and make it look as though your computer has crashed."
Mine's XP so I installed VDMSound.
Thanks for the tip regarding the "OS detection failed". I should have restarted the PC earlier on. Now that I'm going through the first level, I noticed that the sounds are only heard a couple of seconds after the action so I can't know when the enemies are killed since the huge Glidos logo is blocking the centre of the screen. Is that to do with resolution? I've set the game to 800x600 (my PC's 1024x768) full screen. Or the sound settings? I've followed the given settings.
Also, the game flickers to show my desktop while loading. Malfunction? or normal?