Error while uploading

Dear all,

I have been using the x-board from DFRobot (fio) for the past two months with no problems experienced while uploading two types of software codes that I have developped for my project.

Recently, I started getting an error message while uploading any of the software codes to the x-board. I have tried changing x-boards, changing the cable used for the upload and of course, I check the port and the board type before each upload. I have not changed the arduino IDE version, I'm still using the same version 0021 that used to work two days ago, and I have not changed my PC, i'm using windows. Nothing seems to work.

The error message that appears on the bottom of the arduino screen is the following:
Problem uploading to arduino board. See Troubleshooting#upload for suggestions
avrdude: stk500_getsync(): not in sync : resp=0x00
avrdude: stk500_disable(): protocole error : expect=0x14, resp=0x51

Has anyone experienced this error type before?

Any help or guidance is much appreciated.