Vendor tab disappears

[capeinfo]

After many reinstalls, both with and without vm content, the vendor tab keeps disappearing after one appearance as soon as I try to apply or save the edited content.  And nothing is saved.

I kept thinking I had done something wrong but I've tried so many times, so many different ways, I can't figure it out.

I get the following errors:
vmdebug Problem in store TableVendor_medias
vmdebug dangeroustools0

I'm using Joomla 1.5.23; PHP 5.2.17; MySQL 5.0.92

Any suggestions? 

[Milbo]

yeah I am sorry, this is a stupid bug and you did everything right,
already described here http://forum.virtuemart.net/index.php?topic=92039.0 and here http://forum.virtuemart.net/index.php?topic=90927.0

I did this change one week before the release and our internal testers didnt noticed, ...