To evaluate the safety and tolerability of multiple escalating doses of 1263W94 administered orally for 28 days in HIV infected patients with asymptomatic CMV shedding. To obtain preliminary evidence of the in vivo anti CMV activity of different doses of 1263W94 in humans based on quantitative reduction of CMV load in semen and if possible in other biological fluids and to explore the dose response relationship in the anti-CMV activity of 1263W94.