UPDATE: As of January 3, 2013, it seems like Google Drive has a bug described here:
https://productforums.google.com/forum/#!category-topic/drive/HKO3BfkzarI
https://productforums.google.com/forum/#!category-topic/drive/HKO3BfkzarI
If you receive a Google Docs storage full error during sync, here are the steps to troubleshoot this error:
STEP 1: Go to https://www.google.com/settings/storage to verify if you have enough Google Drive storage.
STEP 2: If you do not have enough free storage, please upgrade your storage or go to http://drive.google.com to delete some files.
STEP 3: If you have enough available storage, then you need to verify whether uploading into Google Drive works. Please go to http://drive.google.com and try uploading one file manually via the Google Drive interface. On upload, please deselect “convert to Google Docs format.”
STEP 4: If the step 3 fails, try to delete some files from Google Drive’s Trash. More information on how to manage Google Drive Trash can be found here: http://support.google.com/drive/bin/answer.py?hl=en&answer=2375102.
STEP 5: After you have deleted some files from Google Drive Trash, please try step 3 again. If you receive an error even after deleting files from Google Drive Trash, please contact Google Drive support via their forums: http://support.google.com/a/bin/answer.py?hl=en&answer=2492320.
If you have Google Apps for Business, Government, and Education editions, you can open a support ticket via your Google Apps Control Panel console.
STEP 6: If step 3 is not failing, but cloudHQ is still reporting an error in sync please email cloudHQ support at support@cloudHQ.net.