i have gloves of healing heal 10 ten points a day and cloak of sewers on imoen
a nishruu attacked imoen and drained one charge

now i dont have once a day ability i have 39999 (i dont remeber) charges wow

isold the cloak of sewers for 2000000 huh

some kind of bug

I could see a few glitches like that happening.

Tank1: Wake the Mages, help me fend off this Vampire!
Tank2: Alright, just try to hold 'em back!
Tank1: Eh! He's drained the magical abilities of my sword.. Wait! He's quadrupled them! Ha, ha! Die you evil fiend!

Tank1: You will die Mage!
Mage: *Shoots Lightning Bolt*
Tank1: *Lightning Bolt hits sword, making it into a Vorpal sword*

Its a bug, if you want it to go away(Yeah right why would you want that bug to go away)install the official patch.