I have a problem syncing iCal on my Macbook air (10.7.5) and my iPhone 4s (5.1.1) over iCloud. The following server error message comes up "The request (CalDAVAccountRefreshQueueableOperation) for account “iCloud” failed." Been to Apple - no luck. Ideas?

I have a problem syncing iCal on my Macbook air (10.7.5) and my iPhone 4s (5.1.1) over iCloud. The following server error message comes up "The request (CalDAVAccountRefreshQueueableOperation) for account “iCloud” failed." Been to Apple Store - no luck instore, or with Super genius over the phone when with genius in store, taking data in real time via ethernet!

I had to do a full wipe of my system because of time machine back up issues 2 weeks ago, and the error has only occured at some point since then. I only did a drag and drop of my user account folders/files into an External HDD rather than a copy of my user account (advised by the staff in store at Apple to do this) and when reimported, the Mail folders are all present but each message is in a sub-sub-sub folder that is numerically named. I do not have a mirror image of the hard disk prior to the wipe, only a time machine back up from 2 weeks prior to it being done. I am uncertain if this reinstall has caused the issue.

I am not happy to upgrade the software in my iPhone until I have the calendars working. I have purchased Mountain Lion, but again am concerned about upgrading until the issues are sorted.

I have tried the other solutions on here with no luck. HELP please.

Many Thanks.