Fwd: Apache log: database shutdown

Since yesterday I have following situation.

1) Everything works fine for about one hour.
2) Site didn't show up and apache log is following:

[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_query() [<a href='function.ibase-query'>function.ibase-query</a>]:
database Centrum:Centrum shutdown  in
/var/www/localhost/htdocs/icentrum/php/funkcjewspolne.php on line 215
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_fetch_assoc(): supplied argument is not a valid Firebird/InterBase
result resource in
/var/www/localhost/htdocs/icentrum/php/funkcjewspolne.php on line 216
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_fetch_assoc() [<a
href='function.ibase-fetch-assoc'>function.ibase-fetch-assoc</a>]:
database Centrum:Centrum shutdown  in
/var/www/localhost/htdocs/icentrum/php/zlecenie.php on line 124
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_query() [<a href='function.ibase-query'>function.ibase-query</a>]:
database Centrum:Centrum shutdown  in
/var/www/localhost/htdocs/icentrum/php/zlecenie.php on line 195
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_fetch_assoc(): supplied argument is not a valid Firebird/InterBase
result resource in /var/www/localhost/htdocs/icentrum/php/zlecenie.php
on line 196
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_fetch_assoc() [<a
href='function.ibase-fetch-assoc'>function.ibase-fetch-assoc</a>]:
database Centrum:Centrum shutdown  in
/var/www/localhost/htdocs/icentrum/php/zlecenie.php on line 205
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_query() [<a href='function.ibase-query'>function.ibase-query</a>]:
database Centrum:Centrum shutdown  in
/var/www/localhost/htdocs/icentrum/php/zlecenie.php on line 322
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
ibase_fetch_assoc(): supplied argument is not a valid Firebird/InterBase
result resource in /var/www/localhost/htdocs/icentrum/php/zlecenie.php
on line 323
[Mon Apr 19 14:07:35 2010] [error] [client 10.0.30.10] PHP Warning:
Unknown: database Centrum:Centrum shutdown  in Unknown on line 0

3) Restart apache.
4) Go back to point 1)


I have no idea what is going on. Any help will be appropriated.

Kamil Walas