ACCESS DENIED?!

[xt600]

This evening i've got a new problem when accessing to the forum, this is the message:
Warning: in_array(): Wrong datatype for second argument in /home/xtiweb4d/public_html/forum/Sources/Security.php on line 559
session_start(): open(/tmp/sess_5666e7ff511afa70dd7881c339ceff6b, O_RDWR) failed: Read-only file system (30)
Do you have any idea to help me in troubleshooting? Thanks! 

[xt600]

OK, I helped by myself:
There is a connection/server problem that caused the troubles...

[[Unknown]]

Eep.  Sounds like your server crashed and caused hard drive errors, and then booted up that way.

-[Unknown]

[xt600]

...yes, I think so...

[xt600]

Actually the server is up again and the forum is OK too!