OpenThread() Returns NULL Win32 - c++

Question

I feel like there is an obvious answer to this, but it's been eluding me. I've got some legacy code in C++ here that breaks when it tries to call OpenThread(). I'm running it in Visual C++ 2008 Express Edition. The program first gets the ThreadID of the calling thread, and attempts to open it, like so:
ThreadId threadId = IsThreaded() ? thread_id : ::GetCurrentThreadId();
HANDLE threadHandle = OpenThread(THREAD_ALL_ACCESS, FALSE, threadId);
Now here's what I don't understand: if the thread ID is the current thread's ID, isn't it already open? Could that be why it's returning NULL?
Any feedback would be appreciated.

Answer 1

Maybe you're asking for too much access (THREAD_ALL_ACCESS), though I'd think that you'd have pretty much all permissions to your own thread. Try reducing the access to what you really need.
What does GetLastError() return?
Update:
Take a look at this comment from MSDN:
Windows Server 2003 and Windows
XP/2000: The size of the
THREAD_ALL_ACCESS flag increased on
Windows Server 2008 and Windows Vista.
If an application compiled for Windows
Server 2008 and Windows Vista is run
on Windows Server 2003 or Windows
XP/2000, the THREAD_ALL_ACCESS flag is
too large and the function specifying
this flag fails with
ERROR_ACCESS_DENIED. To avoid this
problem, specify the minimum set of
access rights required for the
operation. If THREAD_ALL_ACCESS must
be used, set _WIN32_WINNT to the
minimum operating system targeted by
your application (for example,
#define _WIN32_WINNT _WIN32_WINNT_WINXP ). For more information, see Using the Windows
Headers

Answer 2

Try using _beginthreadex instead of OpenThread.
Example:
HANDLE hThread;
UINT uiThreadId = 0;
hThread = (HANDLE)_beginthreadex(NULL, // Security attributes
0, // stack
&this->ThreadProc, // Thread proc
this, // Thread param
CREATE_SUSPENDED, // creation mode
&uiThreadId); // Thread ID
if (hThread != NULL){
//SetThreadPriority(hThread, THREAD_PRIORITY_HIGHEST);
ResumeThread(hThread);
m_hThread = hThread;
}
else{
eRetVal = err_ThreadStartErr;
}