Price lost and bundle items lost after changing the deliverytime

Hi,
it happend the second time: I changed the deliverytime in the bundle and updated the product. After this the product is shown as “kostenlos” => 0,– Euro in the shop and the bundleitems are gone. Instead of the bundle items there was one empty item with no productnumber. This item was not to remove. After cache refresh and database optimization I could remove this empty item.
In the first case I recognized the error at the next day during a client ordered meantime the product instead of 1.500 Euro as 0,– Euro – that was the horror.
Today it happened again, that after updating the product the price became 0,– Euro and I thought I have to write you.
Perhaps you have a workround, because without this problem it would be a great helpful plugin – thanks for that.
Thanks for your help.
Best regards Barbara