Incidental "Can not open a resultset"

[heretique]

Hello, everyone.

My application is accessing PostgreSQL 8.1 database (on Windows), and is running constantly all the time. Application has four threads and each one has its own DataModule instance with Zeos components. Each working thread executes simple SQL commands, mostly selects and updates in timely manner: 10 seconds of pause, select, sometimes update, sometimes next select, and pause.

In undetermined time intervals, an exception is thrown: "Can not open a resultset". This happens in all threads, once for several hours. Exception is catched by my application, logged, and in next working cycle (in about ten seconds) everything is fine.

Are there known problems with multithreaded applications?
Or any clues how to diagnose this problem?

[zippo]

I have the same problem in a BDS 2006 + MySQL 5.1 application. No threads here.