what can cause a "object was open" error

Hi,

I am writing an ASP.NET appliction with C#. I also access a MSDE database
with the OleDb Provider. I am using OleDb to have the option of easily
changing the underlying database. That worked all well. But after some
additions to my application I now have the following error:

Exception: System.Data.OleDb.OleDbException
Message: Object was open.
at System.Data.OleDb.OleDbConnection.ProcessResults(Int32 hr)
at System.Data.OleDb.OleDbConnection.InitializeProvider()
at System.Data.OleDb.OleDbConnection.Open()

This error does occur in some code snippets all the time, in some other it
seems that it only happens sometimes. I tried to find out more about the
error by investigating the problem in a code snippet where it always occurs.
But it doesn't help. It is just an INSERT statement to one table. I already
tried synchronizing the code snippet and commenting out all other accesses
to the same table to avoid any collisions by multiple threads that try to
access it, but it still doesn't work. The connection itself is closed, so
"Object" must mean something else. But what? Any ideas?

Regards
Marco