Saying that corporate parent Viacom has lost patience with the underperformance of MTV Networks, the New York Post reported Sunday, citing several unnamed sources, that the company may lay off as many as 500 employees by the end of the week. The Post indicated that morale at the cable unit has collapsed following last summer's firing of Tom Freston as Viacom CEO and that Chairman Sumner Redstone has stepped in to take a more direct hand in running the unit. Today's (Monday) Daily Variety reported that an unnamed Viacom insider had confirmed the layoffs but said that the number is likely to be closer to 250 than 500. The London Financial Times today put the number at 300, adding that some Viacom executives are expecting hundreds more in MTV's international division.