I have EXACTLY the same issue, had issues with downloading excessive data. Uninstalled latest version of widget and latest version of Adobe Air. The I reinstalled them fresh...or tried too. The Met Office Widget failed exactly as yours did. My log looks like yours.
I contacted the Met Office and got this response:
Thank you for your email.
There is a known issue at this time with the Met Office Desktop Widget which is currently under investigation by our IT Team.
We hope to have this resolved shortly and we apologise for any inconvenience this may have caused you.
We just might have to wait they have no date for a fix yet!