I agree that Toontrack did a poor job with this release, and the support was disappointing.  I will say that I was able to resolve the issues (so far, at least) by doing the following.
 
1-Completely uninstall EZDrummer
2-Reboot, do not start Sonar, and re-install EZDrummer 2 AND ANY UPDATES.
3-BEFORE OPENING YOUR DAW, open EZD2 in stand-alone mode and select the Sonar option from the menu in the upper right.
4-Now when you start Sonar and when you open a project, you will get a dialog box asking how many outputs you want.  I always choose 8.  I'm not sure what others do, but I never need more than 6 EZDrummer tracks, so 8 seems to be good.
 
I can't say what will happen to you, but many of us found this to work well.
 
I made a huge mistake by not setting a Windows Restore Point before first installing EZD2.  I will never make that mistake again.  I now set a restore point before I install anything—and I name it something meaningful like "Before_MiniV" or "Before EZD2" or whatever.

Well, I am finished with the drums for our first song and did them with EZD2 loops. Sounds pretty good to me. I didn't have any issues, and I had to reinstall a few plugins after moving everything to the SSD, one of which was EZD2.  It couldn't find a few things,as it was with Nectar and Bias. After reinstalling, it was all ready to go when I opened the project. I am a noob, so take it for what it's worth.

I've own both library since the 2008 and the issues I've had is when using Midi file with other third party Instruments I notice that my file would be alter. what I mean is the project would load and when you played back not all the audio outputs would work.
what you have to do is resign the outputs for each instrument to the right output. this has been an issue since Sonar producer X1 thru Platinum. and when I load a instrument in I use single instrument track, Synth Property Page, Synth Rack View. keep in mind that I told them and send  file screen shot's etc. when I'm working with loop's I never had a problem other than the midi issue every thing else has works well.

FULL DISCLOSURE:  I just remembered that I am still having one issue: sometimes drums come out on the wrong track.  Example: snare, toms, and kick all bleeding into the snare track.  I had to open a separate instance for just the snare.

I guess EZD 2 was released about this time last year.  I upgraded at about the same time as the OP.  Was this a fairly isolated problem that only a few Sonar users experienced?

olemon
I guess EZD 2 was released about this time last year.  I upgraded at about the same time as the OP.  Was this a fairly isolated problem that only a few Sonar users experienced?

The routing issue affected everyone using Sonar, AFAIK.  A workaround was supplied with the update - using the steps Konrad supplied above.
 
The other issues seem to only have only affected a few users.  I was not one of them.

The routing issue was pretty widespread.
 
Other issues, like being unable to freeze/unfreeze VIs (which, of course, prevents fixing the routing issue) does not seem to affect everyone; however, those issues may be related to the number of VIs.  I use 7 to 15 virtual instruments on a song, and some of them are fairly intense orchestral synths.  That may account for the difference.
 
The freeze/unfreeze problem has not happened to me since installing the most recent update ith the Sonar option.  The drums bleeding into the wrong track IS still happening and since there are known In/Out issues with EZD2, this does not really surprise me.  I have been deleting audio tracks I don't need for EZD2: for example, I normally only have Kick, Snare, Hat, Toms, and OH and I delete the other 3 tracks.  I may try leaving the other three, muting and hiding them.  I will report back whether that helps the mysterious bleed issue.
 
Lately, I have been bouncing simple virtual tracks (like shaker) that I don't expect to edit.  Then I drag the wave to a blank audio track and delete the VI. I have fewer problems this way.

Thanks all!  I emailed tech support (Cakewalk) about this and they suggested the re routing thing that many of you suggested.  I don't quite understand the concept of the "Simple Instrument Track" but the tech guy seemed to imply that in a MIDI instrument track there is also an audio track.  Could somebody please clarify that for me.  I'm used to just thinking of it as a MIDI track being played by a VSTI with no audio (per se) involved.  konradh, when I get a moment I will try your suggestion about un installing and re installing EZD 1 & 2.
 
Peace
 
John B

konradh

Other issues, like being unable to freeze/unfreeze VIs (which, of course, prevents fixing the routing issue) does not seem to affect everyone;

I have had this issue too..watched your thread closely. Just never posted. But I only use 3-6 vsti. On any project. Rarely does it get above that.

Johnbee58, I hope it all works out.
 
It sounds like you have a question about Simple Instrument Tracks, so I will try to help.  Forgive me if I am saying stuff you already know.
 
1-An external synth requires two tracks: a MIDI track to send it the notes, volume, etc. and an audio track that plays the sound coming from the synth that is plugged into your interface.  Sonar does not know these are connected or are part of the same instrument.  It is up to you to name them and keep them straight (e.g., Motif MIDI, Motif Audio).
2-Virtual instruments are the same, except that since both the audio track and the instrument itself reside in your computer and in Sonar, Sonar knows the MIDI and audio tracks go together.  If you mute or solo one, the other follows along.
3-When you add a soft synth (virtual instrument) in Sonar, Sonar asks you if you want a Simple Instrument Track, or separate audio and MIDI tracks.
4-If you choose Simple Instrument Track, you will just see one track in Sonar, but in Inspector there will be tabs so you can look at the MIDI or the audio parts of the track.  You can also highlight the track, right click, and ask to split it into an audio track and a MIDI track (but Sonar will still know they belong together).  If you split the Instrument track, you can also have Sonar put them back together again later if you choose.
5-Instead of choosing Simple Instrument Track, you can tell Sonar to create separate audio and MIDI tracks.  You can also choose to have multiple audio tracks and one MIDI track which is a good choice for drums since you may want separate tracks with separate volume, reverb, and EQ for kick, snare, hi-hat, toms, cymbals, etc.
 
A lot of people here always use separate tracks instead of Simple Instrument tracks.  I am mixed.  I use Simple Instrument Tracks for single sounds like Piano or Bass.  I use separate MIDI and audio tracks for drums or string sections when I want to control each sound separately.
 
For RealGuitar, I have two MIDI tracks and one audio track because I want notes for chords on one MIDI track, and keyswitches for strumming on another track.  I do that by telling Sonar to create a separate MIDI and audio tracks, and then cloning the MIDI track before I enter any notes.