I do believe I've found the problem and a ridiculous "fix" for it.
 
A few days ago I posted a message about an error message saying the play/record device is in use or doesn't support the audio format.
 
Last night I was changing pickups in one of my guitars and turned amplitube on just to test them out. A few minutes later, after closing amplitube, I started X2 and damned if the same message didn't pop up. So I closed X2 and opened Dimension, loaded a drum sound, closed it then opened X2 again and guess what? No error message! Last night though there was a slight bit of lag after it starting playing again when I tried playing along or recording.
 
Just a few minutes ago I opened X2 and it worked fine. Curious, I closed it then opened amplitube just to see if it would happen again. Yup, it did. So for some reason all of a sudden either amplitube is still somehow being seen as still running, there's an issue within X2, or Win7 isn't closing programs properly.
 
Considering I haven't seen anyone else complain about this I'm not sure what the problem is. I'm considering a full reinstall of everything. This shouldn't be happening. I run amplitube as a standalone all the time and have never had this happen.
 
Before I take the long drawn out plunge to wipe everything out and do a complete reinstall, any ideas what to try?

did you register amplitube with the IK servers? 

I would not do a complete reinstall..... nope... it sounds like the issue is with Amplitube. 

Be sure it's properly registered and authorised. 

What sound card are you using again? 

And what driver mode on the sound card with X1? 

is there a use drivers exclusively check box in sonar preferences that might help?

In X2 try changing "Share Drivers with other programs" and see if that helps.
If it is on turn it off. If it is off turn it on.

The soundcard is onboard realtek HD, but no drivers are installed for it and it's disabled in device manager. Sonar doesn't seem to support it anyway. I have a Presonus Fire Box exclusively for sound.

All of my Amplitube installs are fully registered and authorized. :)

Tried the share drivers option both on and off and it didn't make a difference.

Driver mode is ASIO.

Another thought... I installed BBE sonic maximizer plug-in too. Forgot about that. It will not show up in the plug-ins or vst list. Wonder if that is causing problems?

if you launch amplitude stand-alone using asio then it will lock the interface.  any program using asio has exclusive access to the soundcard.  launching sonar while another asio application is running will always generate that message. 

He said he "closed Amplitube Standalone, so if he did, it should not interfere with SONAR using the ASIO drivers, unless...

Amplitube is not truly closing.

Check in task manager under processes to see if you see Amplitube in the list. If so, it probably is not closing all the way. You could right click it and close it to most likely solve the problem.

I also agree the problem most likely is with Amplitube, most likely that it is not truly closed out all the way.

Lance

That's what I was thinking too. It's closed completely. Nothing in task manager. If I have to deal with this as it is I guess I will. I do use Amplitube a lot.

What I can't deal with though is the latency that comes along with it now. While I can get it to play and record after getting the error message the latency is consistent.

Maybe the driver is hanging on it.

Try going into device manager and disabling then re-enabling your sound interface driver. Then, open SONAR.

Lance