I stand corrected. The inventory_plus mod by Zeg9 was not the solution either hence I switched to the unified inventory mod. This one is really an improvement because it offers admins the option to grant items to themselves due to the built-in crafting guide. All non-privileged users can see the item recipe instead. It also integrates well with a couple of other mods like worldedit or bags. The server is now a lot more stable thanks to this mod change.
In the past weeks I have learned some things about player privileges, lava and fire. Granting "give" to regular players was an experiment right from the start and I have not been under the illusion that everyone of them would use it responsibly. As it turned out the impact on the game "economy" was quite negative. Some players abused their "fly" and "fast" powers by killing other players with lava buckets or setting wooden buildings on fire and combined with insults this was enough to trigger some permanent server bans. It goes without saying that antisocial behaviour won't be tolerated on this server. If you are aware of players who still behave this way, please contact me.
As a consequence I removed all "give" privileges but I still grant "fly" or "fast" from time to time for really dedicated players. I also disabled the lava bucket and installed HybridDog's fire and lava cooling protection mod. It should be quite impossible to kill other players now. I intend to install some new mods in the near future. More on that topic in a future post.