Some characters lost in serial communication

Hello everybody,

My serial ISR is as below. When I send a string to the microcontroller some characters are not received. The characters are lost in a peculiar way. eg. 1234567890123456 is received as 12356789012456 & 6543210987654321 is received as 65421098765321. Exactly 4th & 13th characters are lost in the mentioned 16 character string, not tested further.

void ISR_Serial (void) interrupt 4      //      using 2
{
        unsigned char in_byte;
        if (RI){                                        // If data is received..
                RI = 0;
                in_byte = SBUF;                         // get character in var
                RxBuffer[ RxInChar ] = in_byte;         // save it in the buffer at RxInChar location

                if(RxInChar==RX_BUF_SIZE)               // if buffer full, (care should be taken by sending app)
                        RxInChar=0;                     // then make it 0
                else if(in_byte==0x0D){                 // whether byte was CR?
                        RxBuffer[ RxInChar ] = '\0';    // & replace it     by NULL char
                        RxInChar=0;                     // then make pointer to 0 (for next transmission)
                        if(!pc_mode_active)
                                strcpy(tmpdata,RxBuffer);
                        ser_data_avail=1;               // set data available flag for main routine
                }
                else
                        RxInChar++;                     // increase the location pointer
        }

        if( TxEnabled ){                                // If data is transmitted
                if (TI){                                // if previous byte is finished transmitting
                        TI = 0;

                        if (TxOutChar != TxInChar){     // adjust queue and transmit character...
                                SBUF = TxBuffer [TxOutChar++];
                                TxOutChar %= TX_BUF_SIZE;//%    is the modulus operator
                        }
                        else
                                TxEnabled =     0;      // nothing else to transmit, so disable function...
                }
        }
}

If I comment out following two lines, there is no problem. (though pc_mode_active is true at this time).

                RxInChar=0;                             // then make pointer to 0 (for next transmission)
//              if(!pc_mode_active)
//                      strcpy(tmpdata,RxBuffer);
                        ser_data_avail=1;               // set data available flag for main routine

The baudrate is 115200. RCAP2H = 0xFF & RCAP2L = 0xFD, in VB I've used "115200,N,8,1"

As pc_mode_active is true at default, the 'if loop' should not execute. Similarly there should not be a problem because the code will reach to this point only on receiveing CR which is at the last position. Please help.

Thanks in advance.