Problem of SPI Read

Hi~
This is a problem about SPI Read Bus in 2686 , when PC send data to 2686 . If PC send 10 Bytes (0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9) every second , SPI Read Bus of 2686 will receive
0xCX 0x30
0xCX 0x31
0xCX 0x32
0xCX 0x33
0xCX 0x34
0xCX 0x35
0xCX 0x36
0xCX 0x37
0xCX 0x38
0xCX 0x39 …
Because there is a IC(Max3100 , SPI to UATR) between 2686 and PC , so this is format of 2686 which receive data .
After several minutes , the data became
0x00 0xCX 0x00 0xCX
0x00 0xCX

0x30 0x00
0x31 0x00
0x32 0x00
0x33 0x00
0x34 0x00
0x35 0x00
0x36 0x00
0x37 0x00
0x38 0x00
0x39 0x00

, then 2686 RESET which became cant work .
I use High Level Interruption to receive data , SPI is 3.25 MHz , BaudRate of PC is 9600 , why became so ? Is that a bug of 2686 ??? or Clock Problems?

Best Regards