Not all my Google Docs transferred well from v1 of the Google Docs editor to the current version. One document with an unusually long table was particularly problematic. Google's cursor tracking was off, and even small edits create ugly formatting artifacts.
I tried exporting to Word, the editing in Word and reimporting, but the results were messy -- though at least editing worked again.
I had more luck with Nisus Writer Pro. I exported as RTF, opened in NWP, saved as RTF and reimported to Google Docs. Then I used a menu command to translate it to GD native format. Seems fine now.
PS. Unrelated quirk -- when I reimported it didn't become associated with Google Drive. I had to search to bring up the new version, then drag to Google Drive to have it show in the Google Drive menu. Google Docs need a bit of usability work