i'm getting the same thing...

Same. Only we don't get the error message. Can't preview, upload or download. Just hangs.

They are dealing with a system wide outage apparently.

Our team is getting the same message. We are unable to open any documents/files/sheets. 

Same thing here. Client can't download files I sent and I can't access them to send them through an alternative. 

Hi Hannah, 

Welcome to Box Community and glad to help! 

We're sorry for your trouble and please note that our Engineering team has identified this issue and updates are posted here!

Thanks for posting!