I cannot open a large project at all. This is a project I worked on for weeks without incident, and now it's six months later and I'm trying to open it and Sonar crashes every time. I tried rebooting the PC and it still crashes on opening. All my other projects open just fine. What should I do????

Try opening in safe mode. This may help you diagnose what is preventing the project from opening. To start in safe mode hold the SHIFT key while opening the project.

Sonar has issues with missing plug-in and missing files. I hope they focus on this area. Another area is exporting, it can crash if Sonar thinks the file path is invalid.

I tried safe mode, and it was exactly the same result. This is a new computer since the last time I opened this project, though other projects opened on this computer that were previously saved on the old computer have opened fine. It's possible there is a plug-in it's using that the others weren't though. I don't have many thirds party plug-ins at all. Like two or three. This project would have to be using one of them I suppose.

I figured it out. There was a plug-in called Magic AB that has caused me some problems in the past. Since I only had 2-3 plug-ins to investigate, I thought that one might be the culprit. I renamed the plug-in's .dll file in Windows Explorer, then opened the project. I got the expected error saying it couldn't load the plug-in, and then the project loaded correctly. I removed reference to the plug-in in the project, saved it, renamed the .dll back, and now everything seems ok.
 

Seems to me this comes up a lot... it would be GREAT if somehow the baker's could modify sonar so it just tally's up or identifies the offending program, disables it, puts up a "Hey... we have a problem here, which is.....blah blah blah" and then loads the project.
 
Sounds easy... I'm sure it isn't or the baker's would have done this by now.  I know that I get a "can't find...." sometimes when I load an old project but...