How to check if your cloud storage service is down
If you can't access your cloud storage service, the problem could be any number of things, from your own computer, to the servers in the cloud. To check if the problem is on the service provider's end, check out the system status pages for your provider. Here are the status pages for Dropbox, iCloud, Google Drive, Box, and SkyDrive:
Dropbox
The Dropbox status page provides the status for Dropbox web access, as well as desktop client access. Details of updates are also provided below the status box. To check Dropbox status, go to http://status.dropbox.com.
iCloudmore