RCA 20" tru-flat tv lost all color.

  RCA Model 20F511T Tru-Flat TV (service code=20F11T-CX61) Lost all color. Perfect B/W picture on all inputs with known good source. color is bright and even with the menues and on-screen info. color level is turned up and all other settings are within normal range. typical story..was working fine and next day,no color. no surges or other power issues that I know of.  set bought 8-23-05. only lightly used (guest room).   any Ideas?  Thanks!