Avrdude error while uploading

Hello,
Would you be so kind and help me with the error I got:

avrdude: ser_send(): write error: sorry no info avail

I have ArduPilot (Diecimila) and try to upload the new software to AT168 via FTDI board.
Today morning everything went fine till I installed Microsoft Visual C++ Express 2005. After rebooting Arduino become slow. Serial Monitor doesnt work either. I unistalled Visual C++ but the problem is still there. Everything is ok on another computer. The problem is that this doesnt work on PC I currently can use.
Please help me
Regards
Michal