Assembly program to get string from user

Hi,
I am trying to learn ASM programming on MS-DOS to get a string from User.
But during the run-time it reboots the OS automatically or hangs or misbehaves while the same program is executed on Windows-XP it does not give any run-time errors.

Could you please help me in this regards as to where am I going wrong.

Below is the environment:
Assembler: Tasm
OS: MS-DOS71, XP

.Model Small
.Stack 100H .Data
    CR Equ 0DH
    LF Equ 0AH
    NL Equ 00H
    MsgX db 32H Dup (NL)
.Code
Run:
    MOV AX, @Data
    MOV DS, AX
    MOV AX, Offset MsgX
    CALL GetStr
    CALL Exit

    GetChr:
        PUSH BX
        PUSH CX
        PUSH DX
        MOV AH, 01H
        INT 21H
        POP  DX
        POP  CX
        POP  BX
    RET

    GetStr:
        PUSH AX
        PUSH BX
        PUSH CX
        PUSH DX
        MOV BX, AX
        GetStrLoop:
            CALL GetChr
            MOV Byte Ptr [BX], AL
            CMP Byte Ptr [BX], CR
            JE GetStrFree
            INC BX
            JMP GetStrLoop
        GetStrFree:
            MOV Byte Ptr [BX], NL
            POP DX
            POP CX
            POP BX
            POP AX
    RET

    Exit:
        MOV AH, 4CH
        INT 21H
End Run

Tags: ASM