Dropouts on one project, not another

I have been working on numerous big projects the last year, and have never had much dropout problem all this time. Today I opened a project I haven't opened in over a year, and even though it's not bigger than many other projects I've worked on, I can't get it to playback without a LOT of very fast stuttering. This is many very short fast stutters, so fast it almost creates a buzzing effect. The project is entirely Midi, mostly EastWest instruments, no audio tracks, no effects, no fancy routing.
 
The Windows Task Manager's Performance monitor shows the CPU maxing out when the project plays back, and the RAM doesn't really change at all, hovers near 50% used. So it looks like my CPU is failing.
 
I have closed other applications, though the Task Manager processes show nothing else consuming CPU, and like I said, other projects of the same size are playing fine, so the issue is not the computer, but this project. Per the help, I messed with Playback I/O Buffer Size, with no change. I cannot adjust the Mixing Latency, as those controls are grayed out.
 
The project contains about 20 EW Orchestral instruments. It is possible that that is more than my other projects, which have easily that many tracks, though some may be my electric piano and rack mount synth box rather than EW and audio tracks, so I guess it's possible this is more EW tracks than any other project, but I don't think so, and it wouldn't be by much. 
 
Windows 7 64-bit
Pentium Dual-Core 2.70GHz
6 Gb RAM 
 
Any ideas?

brundlefly
With ASIO you access settings through the ASIO panel button that launches your interface's control panel.

 
Now running X3d. Most tracks frozen, which improves things somewhat. Still getting occasional pops. This never used to happen with these same projects on the same computer using 8.5.
 
I click on the ASIO Panel... button in Preferences-Audio-Driver Settings, and nothing happens.
 
 
 

I messed with Playback I/O Buffer Size,

That setting will not help you avoid drop outs. That setting is for your Disk %. The reason you are having drop outs for only this project is that your ASIO buffers are too low or your WDM setting is too low for that specific project. All you need to do is raise them, to fix your issue.
 
Every proejct will have different CPU needs and this project demands more CPU than your other projects, hence the drop outs. Just raise your ASIO buffer or WDM slider.
 
CJ

OK - well, turning up the latency by making your ASIO Buffer Size bigger will help for mixing and mastering, where you have finished tracking, BUT you will quickly discover that you could not realistically record tracks with that high a latency.
 
Once you get to a latency of somewhere over 10 milliseconds - like maybe 15 or more, you will begin to hear a lag between when you hit a note and when you hear it play through Sonar.
 
BUT, for mixing purposes, you do not care about that lag, as you are only playing things back. So, for mixing/mastering, you pretty much WANT to have your latency high enough to allow for the extra processing needs of the kinds of plugins that sound soooo good - those that use look-ahead processing or lots of CPU.
 
SOOOO, this will forevermore be something you will have to switch back and forth on - lower latency for tracking, and higher latency for mixing and mastering.
 
Another factor in the equation is how hard your computer has to work at keeping a low latency and still avoiding dropouts - a balance is needed between performance and sound quality.
 
Bottom line: you need to find settings that work for recording purposes, and then afterwards for mixing and mastering you will need to bump those settings up to a much higher latency (which is fine, it's just how it all works).
 
On MY system, I find that the best balance for low latency for recording is:
 
Audio interface: Sample Rate either 44.1 k or 48 k, (I use 48 k), ASIO Buffer Size of 128
 
Sonar: Driver Mode of ASIO, Sample Rate of either 44.1 k or 48 k (must match the interface's setting), Record Bit-Depth of 24 bits.
 
With the above settings, I have an ASIO-reported Total Roundtrip Latency of 9.7 milliseconds, which allows me to record with a zillion tracks and soft synths without hearing any crackles, pops, or having any audio dropouts. 
 
I believe you should shoot for a Total Roundtrip Latency value of at or just under around 10 milliseconds, for good sound quality for recording tracks.
 
Again, once all the tracks of a project are recorded, and I start the mixing process, I turn the ASIO Buffer Size way up, and that allows me to then add in a bunch of heavy-duty effects plugins and still not hear audio dropouts and such.
 
I hope some of the above explains some of this to you, and that you find the above settings helping you record tracks without dropouts.
 
Bob Bone