problem unknown

[grs]

Hello,

If this is not the right forum for my question, please give me the URL to one that is.

I have a strage problem which makes me desparate.
I have a rather complicated C program in Linux, which works well for some time. Then, after several minutes up to an hour, it and its xterm window just disappear.
I see no trace: there is no core dump, I see nothing in the syslog (except for the last message the program logged there), and I'm quite sure that the program does not exit() by itself.
Unfortunately, I cannot run the program under gdb, as it must be run in a xterm, in the home of a normal user, and su to get root privilege.

What could happen? Where may there be a record for what happens ?
The program gives signals to another process, and gets signals from it. Can this be related the problem? If so, how can I know ?

Please Help. Thanks in advance.