it may be related to the (second coming) of the problem here https://premium.wpmudev.org/forums/topic/internal-server-error-all-over-my-site?replies=5#post-1136935 (or even may be the cause) - or not, so I decided to open a new thread.
My server is administrated by LiveConfig and if I check there "Managing Server" and "Databases" I get the following message:
Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
What's to do here?
Thanks in Advance!