Dmitry,

Thanks very much for the response.

> Is only one owner or all owners have the status "hung"?

In the lock print, there were a total of 118 owner blocks, 1 of "Type
1" and 117 of "Type 3".

In all cases of "freezing", the Type 1 block is always "hung", while
usually about 50% of Type 3 blocks are "hung" (in this case 57 or 49%).

In the past, I have left a server for about 20 minutes without
recovery - a reboot was always necessary.

> Do you have anything interesting logged in firebird.log?

Unfortunately not. Only errno = 104 and errno = 110 - which I see all
the time.

What is the difference between Type 1 and Type 3 owner blocks?

Is there anywhere else I could look which might shed some more light.

Regards,
Richard