Unable to open audio playback device - advice needed please

Hi guys,
im currently running sonar 8.0.2, and have recorded about 5 full audio tracks turned of the computer and when the pc was turned back on i tried to play these tracks through sonar and this error message appeared.

"Unable to open audio playback device. Device may not the support the current projects audio format or may be in use"

I have no idea why this message has been shown to me, and any information people may be able to give as to helping me solve this problem would be greatly appreciated. No settings on the drivers or the audio interface have been changed and every other project works fine apart from these 5 full recorded tracks.

cheers, Jim.

the soundcard is a nVidia and using a roland 6/6 channel audio interface, and what do you mean by driver mode? Its been working fine on other projects

thanks 
jim

jim - I know you already said it's been working fine in other projects.  but something's wrong now which could be just a matter of what got the computer's attention first if you have the settings set up so that either will be available.  in the past it was the way you wanted it to work, today it came up differently.

are you using the nvidia onboard soundcard AND the roland?  and what model roland is that exactly?  remember we need as many details as you can give us.

if you don't know what driver mode you're using then you're using the default setting which is WDM and WDM allows more than one soundcard to operate at a time.  that could be the problem.

usually this message comes up when you have a sampling rate mismatch for the project verses the soundcard that is being used for playback/recording.