An internal investigation by the Department of Veterans Affairs has found that one of its hospitals in Jackson, Miss., did not have enough doctors in its primary care unit, resulting in nurse practitioners' handling far too many patients, numerous complaints about delayed care and repeated violations of federal rules on prescribing narcotics. The investigation found no evidence that care had been compromised in the primary care unit, the vital first stop for many patients. But it concluded that there were enough problems "to suggest there may be quality of care issues that require further review," a copy of the investigators' report says.