@tedvanya - thanks for the reply. I wanted to make sure the easy stuff was not an issue.
The Aria software I was able to lookup, and verified it believes it can run just fine in a 64-bit environment.
Can you post a link to the Gigaplayer software you are using?
Also, is your Windows installation up to current patch maintenance levels?
And, do you happen to have antivirus software running on this computer at the same time you are running Sonar? If so, which software is it, and have you tried temporarily disabling it for audio processing sessions using Sonar?
Lastly, please try loading and running this project without those plugins, by first creating a backup of the Cakewalk project file (or the whole folder if you would rather). You can load the project in safe mode in Sonar, and tell it not to load any of the plugins, just as a test to see if things work OK without them.
If the above test works, even though it obviously is crippling to the project, it does serve a purpose, in that it tells you that one or more of the plugins (either effects or instruments) is causing your troubles, and is not a problem with the base Sonar install.
In any case, please post back the results and I will try to assist further.
Thanks,
Bob Bone