Thanks for the reply. I'm using chrome... I checked the chromes extension manager thing, and it said I had the most up to date version of Keychain. I removed it and then reinstalled it just in case, but that hasn't solved the issue.

It does seem odd that the 'publish' button throws up the error, and yet if I click 'schedule' to post in 20 minutes time, the post appears in 20 minutes without a problem

Who knows.... thank you trying anyway