hey evryone!
i’m in the midst of learning to program the robot for next year, and i’m using the OI and RC from 2005 to practice. here’s my problem: i can program the RC, and installed the default code. everything is fine (as far as i can tell with no outputs…just the RC) until i plug in the tether to the OI. when i tether the two, the progam state light on the RC and the ‘code error’ light on the OI start blinking, and nothing works. i havn’t found anything on the IFI website, and i couldn’t find anything here. also, i re-programmed the master code on both, and then reinstalled the default code, and the same thing happened…any advice woul dbe appreciated!!! 
Make sure you step through the IFI troubleshooting FAQ,
IFI FAQ
Some times the code error light will come on when the computer did not finish loading the hex file. I would try loading the default hex a few more times just to verify that your program or downloading method is not causing the error.
The 2005 RC is also different than 06 and 07 RC. So make sure you have the proper default code, or follow the instructions to change the libraries in the latest code.
thanks guys. i found out that the problem was that the code libraries in the default code were wrong, and the help of a [almost] hidden txt file helped me fix the problem.