I can second Lots of Lore in saying that NPC attacks have been behaving oddly for me recently. I had set up some monsters to have a little bit of variability by putting low #s in the attack bonus, and then adding the level and stat to the attack, so that I could just change the CR/Level and/or stat, to increase/decrease the challenge of the monster, based on the groups needs. When I initially set it up, it seemed to work fine. In pre-session testing in the last few days, I kept gettting huge attack results, and the mouse over revealed it was adding the numbers I had put in twice. Then I tried to change the static number for the attack to compensate, changing i.e 6 to 4. In the resulting attack readout instead of d20+4, it was d20+6-2. I discovered then, that unlinking the stat (attack affected by buffs to "STR") negated some of the duplication. I was also able to work around it by deleting the attack that had become corrupted and starting fresh with a new one. Of course, when I tried to get a screen cap just now, I could not duplicate the error precisely. I may have just been messing with it too much. Also, that was on a Firefox browser, which behaves wonky for me sometimes. However, I also have another unexpected behavior: I took the Patrol Security Robot from the AA compendium and duplicated the sheet, then modified it into a different class robot by changing name, CR, stats, AC, etc. For some reason I can't identify, there is a shadow bonus to the creature's AC. The EAC number I have entered is 20, and that is what shows when I click in that box. But the displayed number (and if I call the EAC to a field outside the sheet) is 22. Likewise, the KAC is displayed/calculated 2 points higher than what I had entered.