我做一个串口读写的程序，程序运行一段时间后报错，“指令0x7c9311de引用内存0x00000000,该内存不可“read”,调试按“确定”，结束按“取消””

以下是output窗口中的内容，请大侠指点一下，谢谢了！


Loaded 'ntdll.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\kernel32.dll', no matching symbolic information found.
Loaded symbols for 'C:\WINDOWS\system32\MFC42D.DLL'
Loaded symbols for 'C:\WINDOWS\system32\MSVCRTD.DLL'
Loaded 'C:\WINDOWS\system32\gdi32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\user32.dll', no matching symbolic information found.
Loaded symbols for 'C:\WINDOWS\system32\MFCO42D.DLL'
Loaded 'C:\WINDOWS\system32\imm32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\advapi32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\rpcrt4.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\lpk.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\usp10.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\msvcrt.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\mfc42loc.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\comctl32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\uxtheme.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\msctf.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\version.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\msctfime.ime', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\ole32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\IMSC40A.IME', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\oleaut32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\clbcatq.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\comres.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\version.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\FM20.DLL', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\riched20.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\sxs.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\olepro32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\FM20CHS.DLL', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\msi.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\MSCOMM32.OCX', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\shlwapi.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\shell32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03\comctl32.dll', no matching symbolic information found.
1410. ) 8
) )
1410. ) 8
) )
1410. ) 8
) )
1410. ) 8
) )
The thread 0x49C has exited with code 1 (0x1).
The thread 0x780 has exited with code 0 (0x0).
The program 'E:\QLF\scan_mscomm-1通讯成功后的修改2\Debug\scan.exe' has exited with code 0 (0x0).