I don't know what the problem is, maybe someone else here has seen it. If the error is from the bootloader, then maybe you will have to try contacting the author.

Does your code work okay with a traditional PIC programmer (EPIC, etc)?

Have you tried compiling for different baud rates or oscillator freq? Double check everything too. Make sure you had the right chip selected in MCS, etc. This is the hazard of freeware....limited or no support (you get what you pay for, right?)

BTW - Probably unrelated, but I always try everything I can think of....if you are using 20MHz crystal, then I believe you need to use HS_OSC instead of XT_OSC. Someone else here pointed that out to me on an earlier problem I had.