Rich (I'm guessing XP since you're in SX3),
Not sure I have an "answer", but I know some of the stuff actually installs more than one (different) MOTU driver. For instance, the MIDI stuff will install some "MOTU MIDI" driver when (...if) it sees the interface on boot, but there's another "MIDI for MOTU" or something in the "System" devices area of the DM hardware list.
The fact that you've got some form of Cubase playback, sounds like
something has been installed. If you go into Cubase's ASIO hardware prefs, are you actually set to the specific "ASIO for MOTU 896" or whatever? The other couple options
should be "Multimedia ASIO" or some junk, but I'm not sure they'd show up, if somehow the regular WDM driver hasn't gotten installed (make sure you check that option if there's a pref during the MOTU install). The dedicated ASIO driver for your hardware is almost always recommended for running apps which support it. IIRC, there was one minor issue with exports on Universal Audio PCI card-equipped systems, where people were having less trouble with Nuendo/Cubase being set to the generic driver during their mixdowns, but that real ASIO one is likely the most "glitch-free" for solid multi-tracking.
You sound as if you already know about heading for that "Sounds and Audio" section of the control panel (I think you may even get to some of the same areas via the device manager). Make sure you dig
all the way through it though. If you can find the MOTU in that list (under the hardware tab), and get "properties" on it, you'll be taken to the "driver" properties info for that device. From that window, you should get to the center tab (for "properties"). That box should have all your audio,MIDI,mixer, and audio input devices listed in it, with collapsible list items. If you expand the "audio devices" item in the list (first one I think), there should be a "MOTU something or other" listed under that. Make sure all you've got is "use audio features for this device" checked there.
To insure that it goes for the MOTU, you may also want to try:
* Doing the same thing for your onboard sound driver, but selecting "do not map through this device" in that last panel.
* Go into the "Audio" tab of that first level of the "Sounds & Audio Devices" control panel and set both the playback and recording default devices to the MOTU, then check the "use
only default devices" box at the bottom.
note: Ideally, you should probably just shut the redundant onboard sound circuit off
completely if you can manage it. The BIOS is the best place to do that (if there's an "integrated devices" option or something in there), but disabling the driver via "use audio features on this device" or something may have the same affect nowadays. (?)
Also, try setting your sound "scheme" in the control panel to "no sounds" and/or selecting "do not
map through this device" for your audio hardware. I think even with "map" turned off like that, you can still select the audio i/o devices from either your application's prefs, or that default devices box. ( -? again)
One of the complaints I've heard on that, is that the system sounds,etc. may grab or share the device during DAW work (maybe for common blip/bleep system alerts). They also aren't always at "DAW quality" sample rates, so it doesn't sound like much fun for the audio hardware. People have also recommended actually
using the generic onboard device for that junk, and making sure anything
but the real ASIO software, was specifically instructed to
only use the cheap sound (to allow the real hardware to go "undisturbed"). I guess it's a "Your Mileage May Vary" deal. All that stuff may not matter with XP/ACPI,etc. these days, but limit the sound to that primary hardware, just to see what you get anyway.
Some of the WDM multimedia apps (like WinAmp) will have their own output pref in the options, where you can specify the playback device, but I'm not sure you'll find that in every MediaPlayer version,etc.
My suspicion is the "map through" prefs for that issue you're having with the WDM stuff not seeing the MOTU.
If your main goal is to be running Cubase, I'd focus on getting the dedicated ASIO driver working there first (without those dropouts), then worry about the multimedia crap. Cubase will also have it's own prefs for the buffers,etc. on the chosen audio hardware. You can play around with them, but I really
don't think that even at the defaults, you should immediately be noticing glitches with any host which is even "modestly current technology". Keep in mind, the ASIO access and WDM access are two different things (drivers). It's possible that there could be issues or conflicts with one, which won't affect the other, so trying to tweak, tune, or troubleshoot from outside Cubase (with those multimedia apps) probably isn't an ideal way to approach it, but I guess you'll eventually want to get them both working.
Lastly, try some of the age-old tricks to stop weird crap from any background polling,etc., which may be interrupting your audio streams during Cubase work. These would include disabling the network card, turning down the graphics acceleration, turning off some of the unnecessary services in services.msc (BE CAREFUL), and a bunch of other junk. You can read on some of it at
www.musicxp.net or the RME website (I think).
Hope some of that helps (please post here if it does),
George