I'm am getting the above error now when I try to sync my phone (HTC touch) with our GMS server. It has worked fine and now doesn't throw any errors on the device (just in the web pim ui). Everything but my inbox seems to get updated, just not my inbox.

-I already checked and I am way below the quota for my email account, only using around 16% of 512MB
-Already tried completely removing and then reinstalling the sync client on my phone