I'm using gprolog 1.4.5 (32 bits) on Windows 7 64 compiled without a gui console.
With a locale set to Russian_Russia.1251 is not possible to enter the russian letter 'р'.
I guess the problem is in the terminal.c file in function LE_Get_Char0 here:
c = ir.Event.KeyEvent.uChar.AsciiChar & 0xff;
if (c == 0 || c == 0xe0)
0xe0 is a cp1251 code for the russian letter 'р'.
When i commented this out:
if (c == 0) // || c == 0xe0)
everything seems OK.