Thanx Scolex ... but I still couldn't get other apps to work, even if I closed MC and the MC media server.
This doesn't make sense, but it seems like the Exclusive lock on your sound device isn't being released.
First though, REBOOT (do NOT skip this). That will get everything unlocked and set to a normal state.
My MC17 Audio 'Output mode settings" are enabled for 'Open device for exclusive access', 'Flush device buffers on startup', 'Flush device buffers on pause', and 'Present 24bit data as 32bit package'. I tried disabling these, but got into trouble with tracks not playing and getting a MC prompt to alter "DSP output mixer settings" or I got no sound at all.
Sounds like you tried to disable too much.
So that you understand: The
Open device for exclusive access checkbox does exactly that. While MC is playing something (even paused)
the sound card will be locked to MC and no other applications, even Windows system sounds, will work at all. Windows 7 sometimes gets annoying when you
try to play something externally (maybe browser video) while the sound device is still locked to MC (forgot you had something paused in the background). On my systems, it switches and uses another available sound device for this audio. But, since the device it picks is probably not connected to anywhere, it probably doesn't actually work. So, on my HTPC, it'll switch from my video card's HDMI sound device to the motherboard's SPDIF connection. That's not plugged into anything, so I don't hear any sound. But, if you go down and click on the Volume icon in the System Tray, you'll see a second volume control and meter, and you can see the sound is playing on this second device from the green bouncing up and down. Once you do this, it can be difficult to get Windows to "switch back".*
Most of the time, when you don't "screw up" first, if you just stop playback in MC completely (again, not just paused), your system will regain access to the Sound card and everything is fine. But once you mess up, you usually need to close any impacted applications out completely to get them to switch back to the proper default device (so, you must stop playback in MC and then close your browser and re-open it). But, sometimes Flash crashes and doesn't unload or other stupid things, so occasionally, it is just easiest to reboot (and double-check the default sound device in Windows too, because I've seen
that change "permanently" too).
So, all of this is annoying, right? If you don't want MC use your sound device "exclusively" in this way, then you
must disable the
Open device for exclusive access box in Options -> Audio. But don't disable the other stuff in there as that could break compatibility with your sound device!
However, be aware that exclusive access is what allows MC to bypass the Windows mixer and ensure bitperfect delivery to your sound device directly. So, if you disable that option, then your sound card drivers and Windows will be "able to" mess with your sound (whether they do or not depends on the device you have and the settings in Windows at the time).
If you want to keep exclusive access enabled, you have to understand how it works and be aware of the limitations. You will also want to be careful not to use any
other Windows application that opens your sound device (maybe in the background) and then try to use MC. You want to be especially careful of anything that might do this on boot in the background. Maybe a sharing application or something doing audio analysis or generating thumbnails (not MC, which does it right, but some other dumb program)? This would be terrible behavior for an application, and anything that does it is probably not worth using (and could even be malware trying to "listen in" on you via a mic input), but be careful of that. If something else has your sound device open, and then you try to play something in MC, I can see the sound card driver getting angry (it probably shouldn't, but it might).
* You can probably solve this problem (the Windows switching to another device that isn't used and isn't plugged into anything problem) by simply disabling the other sound outputs in the Windows Sounds Control Panel. If they aren't plugged in anyway, and you're not using them, there is no reason to keep them enabled. Hit the start button and type "sound" (without the quotes) and open the Sound control panel to disable them.
The problem is when you want to keep one enabled for some reason (maybe for Skype use or something similar) and then you mess up and forget MC is paused and then open your web browser and try to play something.