Bug with inventory?

[Sinitrena]

I am not exactly sure if it is really a bug, but, well, here is the problem:
I made an own inventory window on one of my GUI's. I ticked the box "player starts with this item" on some items. First my own inventory window didn't work (I actually made it too small, so this isn't a problem anymore) , but I tried to press tab to start the normal inventory window. The game crashed with the following message:
"An error has occured. Please contact the game author for support, as this is likely to be a scripting error and not a bug in AGS.
(ACI version 2.61.747)
Error: InventoryScreen: one or more of the inventory screen graphics have been deleted."

Now this means that I can't use a costumized inventory window and the standart one in the same game. Is this a bug?
Even if it isn't a bug I think the error message should be something else. It really drove me crazy to find out what the problem was, because according to the error message I thought there might be something wrong with the sprites I imported before this error or with the inventory items I created.

[Gilbert]

It's quite possibly you deleted some of the button graphics of the built-in inv. window (the hard-coded in engine one, not the one customizable in the GUI section).

You have 2 choices:
1. Use a customized GUI for inventory, as you originally did.
2. Add back several sprites, then:
    right-click --> Change sprite number
    and set them to the sprite numbers of the missing button sprites (I think they're 2041, 2042 and 2043).