I have experienced some strange events concerning my inventory. It happens pretty much like this:
1. I have a full inventory
2. I get an item as reward for completing a quest
3. The rewarded item goes into my inventory, but after that I find something from my inventory dropped on the ground
The worst news (for me anyway)is that I lost like this the Harbringer of Kin +1. And I can't find it anymore. Anybody knows the item code so that I can spawn it? And how to actually do it?

If you have a full inventory at the time you get something, it will be dropped on the ground. And there's no way to summon items into the game like with IE games, afaik.

I'm just thinking alound here and havent tested this but might it be possible to load your game in multiplayer with you as the DM then place an item on the ground and save the game. Then reload it in single player and pick up the item?

I can't remember if you can copy multiplayer and single player games between the different save folders (if there are different folders).

Just a food for thought idea.

OF cours make sure you back up your original save in case anything funny happens like losing your character all together.

I'll try! Thank you!
Normally that would be the expected behaviour, but it did not happen that way:
Aawill gave me a cloak of sometihng that I found in my inventory after the conversation was over. On the floor I found 10 medikits, a bag of holding and some other misceleanous stuff I had in my inventory.

I have seen the effect before that causes an item you pick up to be dropped again immediately when your inventory is full. Your experience is somewhat different, I think, in that you are gaining the item through conversation. That means that a script has a CreateItemInInventory command that is used to give your character the item. This must work differently than picking up an item and actual makes room for the item to be created.

Another solution is to create a module with a single area where you place the lost item. After selling off some of your loot so you have some space left in your inventory, save your character. Start the new module up with the save of your character, pick up the lost item, then save your character again. When you next start up the regular module make sure you choose the new save of your character and the item will be in the inventory.

See, easy as pie. :)

Here's an idea...maybe try unloading some of your inventory? :D You seriously have to be packing a lot of crap around for it to be constantly full. Especially when there are so many bags of holding available. Why would you want to do that?

I think I have a solution:
1. Start the DM client
2. Load the saved game
3. Place/create the missing item on the floor
4. Save game
5. Exit DM client
6. Load NWN singleplayer
7. Load saved game
That is pretty much it!
BTW you can cheat A LOT using this method, but it will ruin the adventure INMHO.
Oh, and I need a lot of crap in my inventory 'cause I do not know what might be necessary for a magical item.

As far as I remember right, you can buy in every chapter a few bags, you could store your things in them.