Well, according to a group called "Center for the Study of Sexual Minorities in the Military" (CSSMM: a think tank at the University of California) who claims they have a Pentagon document that has homosexuality as a psychological disorder.
"According to the CSSMM the Department of Defense Instruction that so categorizes homosexuality was signed by the Under Secretary of Defense for Personnel and Readiness in 1996 and re-certified as "current" in 2003.
Although homosexuality has traditionally been considered a psychological disorder the American Psychiatric Association (APA) removed homosexuality from its list of mental illnesses over thirty years ago, claiming that it "implies no impairment in judgment, stability, reliability, or general social and vocational capabilities." The APA’s decision, however, has been the subject of criticism in recent years with some alleging that the 1973 move to remove homosexuality from the list of disorders was highly influenced by homosexual activism and not objective scientific data (http://www.lifesite.net/ldn/2006/feb/06020902.html).
The CSSMM responded to what it has called an outdated and offensive classification of homosexuality by issuing a “report card” on the military, giving it 'F's' in four out of five categories, including "Mental Health Classification," "Anti-gay Harassment and Command Climate," "Evidence-Based Assessment of 'Don't Ask, Don't Tell'" and "Family Support." (source)
Then again, when my mom was in nursing school one of her textbooks listed pregnancy as a disease...