I did send a mail,and expect soon some answer.Thanks for your care.I don't think it's all about my PC,because I repeat,it happens only in that part of the quest,I played all of quests and had never such problem...
By the way I tried it in a few browsers(Mozilla 3.6.3.--Opera 10.53---IE 8,G-Chrome---Safari---)and it happens the same thing on the same way.Here is my informatio about the PC:
-OS Microsoft Windows XP Professional-SP 2
-DirectX 4.09.00.0904 (DirectX 9.0c)
-Processor AMD Athlon XP, 1700 MHz (8.5 x 200) 2200+
-System memory 1280 MB (PC3200 DDR SDRAM)
-Graph. NVIDIA GeForce FX 5200 (128 MB)
-Audio- Realtek ALC655 @ VIA AC'97 Enhanced Audio Controller