Try a 40 second reset. Then you should be able to see your dashboard. It would be a good idea to downgrade your firmware to v3, which is much more stable.
Then, disable the unnecessary scanning services. Read about it here:
http://community.wd.com/t5/WD-My-Cloud/Hidden-wdmc-directories-created-by-mcserver-and-photodbmerger/m-p/682091/highlight/true#M7765