Q&A for How to Complete the Mind of Madness in Skyrim

Find Dervenin in Solitude (near Proudspire Manor and Hall of the Dead). Agree to help him and head to the Blue Palace. Request to enter the forbidden wing (Falk) and go upstairs to the misty hallway. Sheogorath will bring you to his realm and give you Wabbajack. Use it to complete the trials. Arena Trial: Hit one of the guys sitting in the chairs across the arena - they turn to wolves. Nightmares Trial: Hit Pelagius with Wabbajack and strike each enemy to turn them into something non-aggressive. Confidence Trial: Shrink the soldiers attacking Pelagius and increase Pelagius' size, using Wabbajack. Check out UESP.net if you need more help.

Problem: You fast-travelled, which therefore caused an error in your game, and it is now unable to be completed. Do not leave the area until you've completed the trials. Check UESP.net for a walkthrough if you need a tip or two. Solution: You will need to reload an older save from before you fast-traveled.

Freezing is common in TESV. Quit and reload an old save, then save before reaching the freezing point.

You're not supposed to go back after you finish the quest. The area you enter is a "one-time" kind of deal. If you would like to go back, go to a save before you did the quest and repeat it.