Error opening BCD Registry "Boot configuration data store" not found


On some computer EasyBCD works find.
On otheres there are problems.

When I e.g. call EasyBCD v2.0.2 from WinXP+SP3 on a computer with the following two partitions:

C: primary with WinXP
D: extended/logical partition

Then at first a warning popsup teling me:

"Error Opening BCD Registry
The boot configuration data store could not be opened.
The system cannot find the file specified
Would you like to manually load the BCD registry for EasyBCD to manage"

Hmm, why can EaasyBCD not find the boot files ?
WinXP starts fine for months. So there must be somewhere a boot config file

Does such a boot config file only exist when there are MORE than 1 bootable OS available?

Where should I tell EasyBCD to search for the files?