Daniel,
Since you've been using this unit for over a year without fault, I'm going to assume that you have the right Mic input selected, have the mic connection(s) firmly in their inputs and the gain set properly.
However sometimes accidents happen, so just double check those to make sure that they are indeed still set properly.
According to M-audio's manual for this unit it is NORMAL for the s/pdif's input and output to glow steadily (Even when not in use) and the input to become intermittent when IN use. So it is unlikely that the s/pdif is the culprit here.
Once we have determined that all of your NORMAL settings are still accurate we need to troubleshoot here.
Are there any changes you made to the system about the time that the problem started?
Reinstalled the OS? Installed or uninstalled Audio related Hardware/Software etc......?
Check in the Device manager(if you need direction on how to do so then comment back and I'll describe the procedure)
I'm not sure if this will be under Firewire adapters or under the Sound Game controllers so check each spot. Is there an exclamation mark in a yellow circle next to the devices entry? If so then you have a driver issue
Drivers can be found here. just select your unit and Windows XP SP1/SP2/SP3 depending on which one you have.
http://www.m-audio.com/index.php?do=support&tab=driver
You might try this even if there isn't a driver fault shown.
Right click the driver in device manager and select uninstall. Once this is uninstalled the system will likely ask you to reboot to FINISH the uninstall. Now download the appropriate driver for your unit. After the reboot install the new driver and check to see if it's working
If it Still is not working. Your likely fault is an electrical one. try using a different MIDI or Firewire cable (Depending on how you connect to your PC)
If thats not it TRY a different Mic on your Input
If that STILL is not it then the problem is likely IN the unit itself, Unless your comfortable dealing with high voltage electronics, I think this is where a service department should come into play.
Hopefully you find this helpful, and please don't let your bad experience on the CHATS affect how you feel about Fixya
Any questions you have regarding that may be directed to
[email protected]
Hope this helps you
Dave