Severe problems with ColdFusion 5, ODBC and PostgreSQL 7.2.1

Hi!
 
We've recently migrated our frontend database from Oracle on Win2k to
PostgreSQL 7.2.1 on SuSE Linux 7.2.1. Everything is running - most of
the time. But about once every hour, at least one of our three
webservers running ColdFusion 5 is throwing one of the following errors:
 
ODBC Error Code = IM005 (Driver's SQLAllocConnect failed)
[Microsoft][ODBC Driver Manager] Fehler beim SQLAllocHandle-Aufruf für
Treiber auf SQL_HANDLE_DBC.
(Error calling SQLAllocHandle for Driver on SQL_HANDLE_DBC).
 
respectively:
 
ODBC Error Code = S1000 (General error)
The database does not exist on the server or user authentication failed.
 
I've got to restart the ColdFusion Application Server service in the
services control panel before the server starts working again. It seems
like it just forgets how to connect to the databases from one moment to
the next. I don't really know what exactly is going on, so could anyone
give me some hints on how to determine the cause of all this and how to
resolve the issue?
Thank you very much!
 
Regards,
Markus