Hi Barry,
Thank you for your help,
This program is started from a "scheduling application"
It doesn't have a graphic interface and it use an SQL Database.
The very strange thing is that I installed it on 5 machines;
On 3 machines the application work well, and on 2 machines the
application failed every 2/3 day (!).... with the error in subject

[Application info]
App. C# ... start at least 1 thread (max 3)
Read/Write on SQL Server.
"Speak" with a C++ application throught a C++ wrapper.

Thank you very much.
//Luca