Hello tuti14,
It sounds like you are getting this pop up over and over saying your computer cannot connect to iCloud becuase there was a problem. I recommend these steps from the article named:
Resolve Back to My Mac status messages in iCloud preferences
http://support.apple.com/kb/ts4104
Your computer can't connect to the iCloud service.
- Deselect the Back to My Mac checkbox in iCloud preferences, wait 15 seconds, then select it again to turn Back to My Mac back on.
- Check the System Status page to make sure that there are no issues listed for Back to My Mac.
- Determine whether your Internet Service Provider (ISP) is experiencing a service outage.
- Make sure that the TCP or UDP ports used by Back to My Mac are open on your firewall. Contact your ISP if you need help confirming that these ports are open. If you're in a corporate network environment or other organization where your Internet connection is managed for you, contact your network administrator to make sure that these ports aren't blocked.
If this does not resolve the issue I would next boot into Safe Mode, and then sign out of your iCloud account in your system preferences, restart the computer and try again.
OS X: What is Safe Boot, Safe Mode?
http://support.apple.com/kb/ht1564
Thank you for using Apple Support Communities.
Regards,
Sterling