Okay, there's basically two XP counts:
- NWN XP count, which you see on your character sheet, and which controls your level.
- PotM buffer XP, which controls how much XP actually goes to your NWN XP count; but you can't check this count except through the rest message.
When you get enough XP for a new level, for example going from level 13 to 14, the PotM buffer will deduct 14,000 XP from itself, and add 14,000 XP to the NWN XP count. Equally, when you lose a level, the buffer will deduct 14,000XP from your NWN XP count -- which is what you see on the screen.
So basically this is what happened:
* the enchanting process checked Sudhri's XP level and saw that she didn't have 11,000 XP in her buffer to pay for the enchantment -- let's say for the sake of argument she only had 6,000 XP.
* She needs more XP then, and the XP buffer needs to get this from the NWN XP count. So it makes Sudhri go down a level.
* But this doesn't just pass to Sudrhi's buffer the XP she needs -- it will pass all 14,000 of level 14 to the XP buffer.
* Sudhri's buffer will now contain 20,000 XP (the original 6,000 plus 14,000). From this, the enchanting process deducts 11,000.
* Sudhri is now left with 9,000XP in her buffer or so, but this remains uncheckable as per the buffer functionment.