> How can it happen un-theoretically? Is "not cleanly finished"
> something from my code or something from the Server?

From the driver. Not all sensitive parts are protected with try/finally,
when a runtime exception happens or server sends a so-called fatal error.

> Is there a workaround.

No. Main problem is that this bug is hardly reproducable. I'm trying this
for more than one year now. Most of the cases were fixed, but your report
shows that not all.

Roman