I tested several ATMEL 89C55 and 89S8252-24 PC working with 20.48 Mhz xtal and in all, the same problem, but I managed to use timer1 to toggle a pin by software, with this, the problem disappears. The problem is only in timer 2 in clockout mode with EA=1, anyway now my project is working. But I'm thinking to write to Atmel guys...
Thaan you all
Gustavo