"My hard drive is 5-600GB and I have 82GB left."


Well this could be the problem. 


I would clean that out as much as possible and de-frag. 


"And again lastly, any idea why the project file is so huge in comparison to usual?!?!?!"  



4 MB is not huge. A 3 minute song on a CD is around 40MB. 
So unless you are talking 4 GB your files are very small. Mine are all between 300MB and 600 MB. And we are talking the project containment folder for the CWP and audio folder. 

I should have been more clear, sorry.

Close SONAR and any other open programs. In Windows Explorer, navigate to the folder above your project folder. Right-click on the folder and select "Copy". Then click in the white space between icons and select "Paste". You'll get a copy of the project folder with a name like "Copy of {Project_Name}".

Open SONAR and open the project in the "Copy of ____" folder. 

One of these things is going to happen:

1. The copy/paste will fail because there is a corrupt file in your project that Windows cannot read. Explorer should tell you the name of the bad file, in which case you should rename it to "Corrupt File Do Not Delete". Don't delete it until you've had a chance to back everything up and run a disk repair.

2. The copy/paste will complete and the newly-copied project will open and save with no errors, in which case you rename the original project "Corrupt Project Do Not Delete" and carry on. After you've backed up and run a disk repair, you can delete it.

3. The copied project will fail to open or save, in which case you've got serious disk corruption, either a corrupt wave file (hopefully, because you can figure out which one it is and delete it), or a corrupt project file. If the latter, you're pretty much screwed unless you want to start a new project and import each file one-by-one.