Use Mutex instead of Critical Section. There is a little difference between mutexes and critical sections - critical sections are more effective while mutexes are more flexible. Your can easily switch between mutexes and critical sections, using for example mutexes in debug version.

for critical section we use:

var
  FLock: TRTLCriticalSection;

  InitializeCriticalSection(FLock);  // create lock
  DeleteCriticalSection(FLock);      // free lock
  EnterCriticalSection(FLock);       // acquire lock
  LeaveCriticalSection(FLock);       // release lock

var FLock: THandle;

FLock:= CreateMutex(nil, False, nil);  // create lock
CloseHandle(FLock);                    // free lock
WaitForSingleObject(FLock, Timeout);   // acquire lock
ReleaseMutex(FLock);                   // release lock

function AcquireLock(Lock: THandle; TimeOut: LongWord): Boolean;
begin
  Result:= WaitForSingleObject(Lock, Timeout) = WAIT_OBJECT_0;
end;

while not TryEnterCriticalSection(fLock) and (additional_checks) do
begin
  deal_with_failure();
  sleep(500); // wait 500 ms
end;