Error Out of sync

[sor1]

Sometimes, for a not identified reason, I get the error:
"Something has caused us to be out of sync with the server. Take not of any unsaved data, and click here to re-sync."

I am connected to Activiti-Explorer with a user "X" and nobody else is using this account.
To get rid of the problem, I have to delete the cookies on my PC.

Have you got an idea why I get such a message?

[yz250]

Hi I' ve got the same problem and it shows where i switch too fast pages or labels on the main bar of activiti.
I' ve got 2 setup of activiti, one on localhost and the second one on a server and with both of them I get this error, so I think is a bug or something that need to be fix in the activiti engine.

Ivan.