Post that file to a pastebin site and post the URL to your document here. (It's available in the boot-info-script package in Ubuntu.) This will generate a file called RESULTS.txt. In any event, if you want a more thorough diagnosis, I recommend booting a Linux live session and running the Boot Info Script. OTOH, that could be a gptsync bug or some minor issue that's not worth worrying about. That said, you've got at least one other symptom that disturbs me a bit: the gptsync issue, which might denote a serious partition table problem. rEFInd may help because it can detect and launch Linux kernels directly, whereas rEFIt relies on an EFI or BIOS-mode boot loader - and based on the error message, it sounds like it's trying to launch Linux in BIOS mode but is running into problems with the boot loader.

(Note: I'm rEFInd's maintainer.) If you want to play it safe, you can try rEFInd risk-free by using its USB flash drive or CD-R version (both available from the downloads page). One shot-in-the-dark solution is to replace rEFIt, which has been abandoned for over five years, with its maintained fork, rEFInd.