Not sure that error is relevant to the problem I'm having, it seems to be something to do with updating, so I tried doing just that.
I now have version 4.5.523. I rebooted as requested and had no error. Tried downloading mail, and eveything was working as it should.
I then had a vague recolection that this occured when first upgrading to version 4.5. It was only after shutting down and then restarting the PC the following day that I first got the error. With this in mind, I shut down the PC and restarted, and guess what? the same error is back again, and no new entries in the log file.
Any more suggestions, anyone?