"Memory model: Large" works incorrect

I have ADuC847 (8051) microcontroller. You provided our partner with trial version of C51 compiler.
If I select Small memory model, my unit works perfect.
But if I select Large memory model, it works incorrect.
Program size: data=12.0 xdata=93 code 924
As I discovered PLDXDATA affects my 'P0' port value and the program goes in unknown way.
Here is the piece if code:

59: void OutputLED(unsigned char val) 60: { 61: P0 = ~val;
C:0x037A EF MOV A,R7
C:0x037B F4 CPL A
C:0x037C F580 MOV P0(0x80),A 62: }
C:0x037E 22 RET
// Then the following code runs:
C:0x0309 7B00 MOV R3,#0x00
C:0x030B 7A00 MOV R2,#0x00
C:0x030D 7900 MOV R1,#0x00
C:0x030F C003 PUSH 0x03
C:0x0311 C002 PUSH 0x02
C:0x0313 C001 PUSH 0x01
C:0x0315 90001F MOV DPTR,#0x001F
C:0x0318 12006D LCALL C?PLDXDATA(C:006D)
C:0x031B 120096 LCALL C?PSTPTR(C:0096)
// PLDXDATA has the following ASM code: C?PLDXDATA:
C:0x006D E0 MOVX A,@DPTR
C:0x006E FB MOV R3,A
C:0x006F A3 INC DPTR
C:0x0070 E0 MOVX A,@DPTR
C:0x0071 FA MOV R2,A
C:0x0072 A3 INC DPTR
C:0x0073 E0 MOVX A,@DPTR
C:0x0074 F9 MOV R1,A
C:0x0075 22 RET

// BUT command "C:0x006D E0 MOVX A,@DPTR"
// affects my P0 state. Before it was EF and afterwards it changes to FF.
Could you give me a hand with it?