Dave Matthews has put his celebrity behind an effort urging Congress to ensure US troops traumatized in combat get the medical and psychiatric help they need.

"It just struck me as a profound injustice that someone who had given so much of themselves and clearly showed such a quality of personality that the gratitude we're showing them was basically a dishonorable discharge," Matthews said in an interview which aired Sunday (7/15) on ABC's "This Week" program.

Matthews said that a petition on the band's website has accumulated 23,000 signatures so far. The petition asks Congress to investigate reports that some returning soldiers' mental health problems have been misdiagnosed by the military as pre-existing conditions, rather than having been caused by service-related trauma.

A government task force recently found that at least one-third of returning combat veterans suffer from a variety of service-related problems, including traumatic brain injury and post-traumatic stress disorder. The task force urged stronger leadership, more funding, and a greater emphasis on prevention and screening.

The Dave Matthews Band [ tickets ] is preparing to kick off a long summer tour, launching a two-month, 28-city outing with an Aug. 1-2 engagement in Mansfield, MA, a suburb 30 miles south of Boston. The trek includes a Matthews solo acoustic performance at the 2007 edition of Willie Nelson's Farm Aid festival, which is set to take place Sept. 9 in Randall's Island, NY.

DMB's complete tour schedule is included below.