Issue began while trying to upgrade to version 3 from 2.8 using WordPress.
After Admin log-in, just get blank screen.
Was informed later that v3 is not compatible with the version PLESK my hosting company uses.
I tried to replace all files from back-up prior to upgrade and get the following error message:
Parse error: syntax error, unexpected T_ENCAPSED_AND_WHITESPACE, expecting T_STRING or T_VARIABLE or T_NUM_STRING in /...wp-admin/includes/media.php on line 321
All data appears to be intact. Files are still visible and functioning properly to the public. But all admin access is unavailable.