Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
iWork For iCloud Beta Now Available
In the last couple of weeks Apple has been sending more and more invites out to users accepted ing them to the iWork for iCloud beta.
Any user with a valid Apple ID can now login to iCloud via the usual login in page and will three new icons including, Pages, Numbers and Keynote these will load the relevant program within your browser no matter what device you are on.
Apple recently redesigned the iCloud website platform to make it fit the with the design of iOS 7. Apple is expected to release iWork for iCloud this fall alongside iOS 7 and OS X Mavericks.