GTA IV's paint shop has a 'cursed' color that traps your car in an infinite loop.

Excessive use of Pay 'n' Spray can trigger a paint loop glitch where certain vehicles get permanently stuck respraying the same dark metallic color. This happens because the engine — carried over from San Andreas which lacked metallic paints — can't tell pearlescent colors apart and enters a '20 GOTO 10'-style infinite loop.

Source: Glitches in GTA IV — CC BY-SA