Cannot set cron jobs

[GregyFun]

My 3 cron jobs have disaperared...

I have this error on the page :

/usr/bin/crontab permissions are wrong. Please set to 4755

I cannot set any cron job...

Help please!
Edit:
And now I have a beautiful suspension :

Error:
The hosting account does not exist. It may have been terminated.

Can someone explain?!?

 

[Xemnas]

Does your FTP work? Does any other part of your site function?