Is this on 1.8.0-rc2 CMS and windows 1.8.0-rc2 client?
So it would seem that it connect to the CMS every hour, that would seem rather odd, assuming that your collection interval in a display profile assigned to your device is not set to 1h of course.
You can also double check that timezone in cms, server, client PC are all the same and correct.
Today i make it a bit easyer then yesterday. I think my Xibo-installation ist damaged, so i make a fullbackup of the DB an Files. Set up a new installation of Xibo on a new webserver. So i have a look an that Problem (for now the problem is gone).
We look further whats happen in the future… I report wenn everything is wrong about that.