Last night I suddenly got a message that Sonar was unable to open the record device. It may be in use by something else.
 
I simply unplugged my Presonus and plugged it back in. Seemed to work last night, now nothing works. Same message every time and on every project. I checked the settings and they seem fine.
 
Only thing different that I can think of is I tried opening the cakewalk Parametric EQ. Every time I tried it crashed and I'd have to force close Sonar.
 
I've checked other audio programs and they work fine. Sonar is the only one that can't play anything.
 
Any ideas what the hub-bub could be?

It sounds like you may have something else on your machine "taking hold" of your device and not allowing it to be shared. 

What OS are you using? Somewhere in Control Panel, you can find the area that lists audio devices and its drivers. It will list what the preferred device for recording is, etc. I can't describe it fully right now, as I'm on a Mac.

Check through that section to see if it is your preferred device. Also, could one of the other programs that you have be "holding" it in the background. You could probably discover this via Task Manager.

It's a custom machine I built specifically for Sonar running Win7 64bit. It's stange because it just started happening. The only recording software I have installed is X2.

I've already closed everything audio related, excluding X2, in task manager. I'll check the recording devices just to make sure.

Everything looks normal and the devices set properly. The presonus is the only audio device I have connected. The onboard audio is is disabled and no drivers ever installed for it.

I'm thinking somehow that EQ plugin hosed it. That's the only thing that happened before this message started popping up.

The actual error says, that is can't load either the audio or record device. The audio format may not be supported or is in use by another device.

make sure the presonus is set to 44.

It was actually on 48 for some reason and sonar on 44, but has been fine. Now they are both 44 and same thing happens.

I got it running again. Not sure if it's a fix or just a band-aid. I did a system restore and that unlocked it. The only thing that happened the of the issue was I installed addictive drums and tried applying the cakewalk plug-in.

After the restore though, the plug-in still locks Sonar up and I have to force close it. Strange the only plug-ins giving me problems is cakewalks...

This happens to me if I turn my (MOTU 828Mk2) interface off and back on again. I'm always careful to power on the interface before booting the computer or bringing it out of standby. I'm not sure if it's the interface, its driver or the firewire driver that's at fault, but sometimes I can bring it back to life by unplugging the firewire cable and re-inserting it after a couple seconds.