The worst i've had so far was a glitch where after a Skylander died, it kept the message on screen through the rest of the chapter that the Skylander needs to rest and to press Y if you want to restart the level. It didn't matter what Skylander I put on the portal, the message stayed up.
It got rather annoying since it was the next-to-last crypt level that has all the cannons, so every time I needed to turn or fire a cannon it performed that action as well as brought up the Yes/No screen to restart. Made it through the level without needing to do so, and things returned to normal once I was back in the overworld.
Avatar, Bolt, Cars, Lego Batman, Lego Indiana Jones, Lego Indiana Jones 2: TAC, Lego Star Wars: TCS, Open Season, Viva Piņata: TIP
Battlefield 1943, Defense Grid, Rocky and Bullwinkle