Couldn't add extra OpenSSL entropy

[mephivio]

HI all,

Since a few days, if i (re)start the service vsftpd, all works fine.
After a few minutes, i can't connect again to my server from ftp. (only a restart repairs it for a few minutes again)
if i read my vsftpd.log, i see this error message : Couldn't add extra OpenSSL entropy ....
any idea ?

should i have to recompile my openssl ?
witch with parameters ?

Thanks for your help, i appreciate