I saw that some people on the WotC forums were making posts regarding to adjudicating critical failures on skill checks. The rules below how we roll critical failures in skill checks in our games.
How to Determine a Critical Failures on Skill Checks
Whenever a character rolls a natural 1 on a skill check, that individual has done so poorly that something bad must befall him. If the character is trained in the skill to which he was using when he rolled a natural 1, roll another d20 and if the result is anything but a 1, that player is considered to have failed that skill check, but no abnormally poor result come about from it. If that player rolls a 1 on the second d20 roll, the skill check is a critical failure.
For players who are untrained in the skill to which they rolled a critical failure and if the player's race grants the player a skill bonus to the skill then, roll another d20 and make a save against bad luck (a roll of 11 or higher is a success).
If the player's race nor the player's training grants him no bonus in the skill, then the first roll of a 1 is considered a critical failure without any second roll.
What happens in cases of Critical Failures on Skill Checks
If you roll a critical failure as part of an extended skill check, the failure is considered to count as two rather than one failures. If you roll the critical failure as part of a standard skill use then any damage that would be taken as part of the fail is automatically considered maximized. If the skill is a knowledge skill being used in combat, then the result causes the individual to recall misguided information. If the result is for things in the case of stealth or thievery, the player believes that he has succeeded whereas the target knows that he has failed and thus gets the jump on the player. From this direction other skill checks can then be adjudicated as necessary.
You cannot roll a critical failure on knowledge based skill checks outside of combat.