[Solve] Problem AH00558 When Restarting Apache2

I'm trying to restart apache2 using this command:

sudo service apache2 restart

or

sudo /etc/init.d/apache2 restart

But get below error:

AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1.

So, how to fix this problem?

[Solve] "The mcrypt extension is missing. Please check your PHP configuration" Phpmyadmin Error in Ubuntu 13.10

I've done installation phpmyadmin on Ubuntu 13.10 with apache web server. I restarted apache2 and after login to phpmyadmin, on the bottom of the page show this error: "The mcrypt extension is missing. Please check your PHP configuration." like screenshot below:

So, how to fix this problem?

[Solved] "/bin/rm: cannot remove `/run/user/root/gvfs': Is a directory" When exit from root / superuser

This problem occurs when we have entered in the root or superuser, then when trying to exit, show this information "/bin/rm: cannot remove '/run/user/root/gvfs': Is a directory" like image below:

So, how can fix this?

[Solved Problem] "GDBus.Error:org.openobex.Error.failed: Unable to request session" While Send File via Bluetooth in Ubuntu 13.04

In Ubuntu 13.04 have a problem while send file via Bluetooth to other devices. What the error description? The error description like image above is "GDBus.Error:org.openobex:Error.Failed: Unable to request session".