FireBirdCS-2.5.5.26952
Intel® Core™ i7-2600 Quad-Core inkl. - 4 ядра, 32 GB DDR3 RAM, 2 x 3 TB 6 Gb/s HDD SATA3
Debian 6 Squeeze 64 bit
Work the database is on a separate 250 GB 6 Gb/s SSD

At last week in log this messages:

============================================

serv    Tue Feb 28 05:13:13 2017
    Pthread Error
    operating system directive pthread_mutex_destroy(event-> event_mutex) failed
    Device or resource busy

serv (Client)    Tue Feb 28 05:13:13 2017
    /opt/firebird/bin/fbguard: /opt/firebird/bin/fb_smp_ server terminated abnormally (-1)

serv (Client)    Tue Feb 28 05:13:14 2017
    /opt/firebird/bin/fbguard: guardian starting /opt/firebird/bin/fb_smp_ server

serv (Client)    Tue Feb 28 05:13:14 2017
    INET/inet_error: connect errno = 111

serv (Client)    Tue Feb 28 05:16:58 2017
    REMOTE INTERFACE/gds__detach: Unsuccesful detach from database.
    Uncommitted work may have been lost

============================================

This was set up to 2.5.0 from official depository of Debian, was errors:

============================================
serv (Client)    Sat Feb 25 03:57:41 2017
    INET/inet_error: read errno = 104

serv (Client)    Sat Feb 25 03:57:41 2017
    REMOTE INTERFACE/gds__detach: Unsuccesful detach from database.
    Uncommitted work may have been lost

============================================

Support of DataCenter reported a large load on the local drives, installed SSD drive and move database on this drive

Make a full system test - normally say it.

Reinstalled 2.5.0 on 2.5.5. - errors are less likely, but it's still left.

What to do at least tell me :-(