Launch default web browser to open HTML file

I want to programmatically launch the default web browser to open an HTML file, but I can't get it to work.  I am trying to do it by calling CreateProcess and passing it the command:

start "" /I "File Path.html"

This works when I type it on the command line, but not when I use CreateProcess.  CreateProcess() returns FALSE and GetLastError() returns 123 (The filename, directory name, or volume label syntax is incorrect.)

I see that start is not a real executable, so I tried it with cmd.exe like this:

cmd.exe /c start "" /I "File Path.html"

with the same results, so I tried it with the full path, like this:

c:\windows\system32\cmd.exe /c start "" /I "File Path.html"

but still I get the same result.  Here is my code snippet, what should I do to accomplish this task?

--------------------------


//CString sFilePath is defined before this point
//it is an output file of another operation
//I am confident that the file path is correct and complete
//open the output file using the default web browser
//by executing:
//cmd.exe /C start "" /I "FilePath"
CString sFullCommandLine;
//TODOLATER: read the appropriate path from the registry
CString sCmdExePath = "c:\\windows\\system32\\cmd.exe";
sFullCommandLine.Format("%s /C start \"\" /I \"%s\"", sCmdExePath, sFilePath);

PROCESS_INFORMATION ProcessInfo = {0,0,0,0}; //receives info about the launched process

STARTUPINFO StartupInfo; //specifies window creation info for CreateProcess()
StartupInfo.cb          = sizeof(STARTUPINFO);
StartupInfo.lpReserved  = NULL;
StartupInfo.lpDesktop   = NULL;
StartupInfo.lpTitle     = NULL;
StartupInfo.cbReserved2 = NULL;
StartupInfo.lpReserved2 = NULL;
StartupInfo.dwFlags     = NULL;

BOOL bSuccess = CreateProcess(
    sFullCommandLine,   //App Name
    NULL,               //command line
    NULL,               //security attributes
    NULL,               //thread attributes
    TRUE,               //inherit handles,
    NULL,               //creation flags
    NULL,               //environment
    NULL,               //working directory
    &StartupInfo,       //startup info
    &ProcessInfo);      //lpProcessInformation