Failing to set COM+ ConstructorString on Win7 - CryptProtectData changes?

UPDATED

I'm trying to programmatic-ally set a COM+ component's ConstructorString with a value for later initialization.

The code in question works fine on WinXP, Win2k3, Vista and Win2k8.

I'm failing on Win7 - Home Premium version.

I've determined by trial and error that there seems to be a size limit on the constructor string - if the string is 512 characters (wchar) or less, it saves. Longer, and the SaveChanges call on the CatalogCollection object fails with a 0x80110437 - COMADMIN_E_PROPERTYSAVEFAILED error.

Turns out, all systems have that limit - 512 characters.

We use CryptProtectData to encrypt a password before putting it into the string.

On win7 (x64) the output of the string is longer than on XP (x32) and W2k3 (x64).

So - CryptProtectData has changed - why is the output longer?

    if (!CryptProtectData(&dataIn,L" ",&optionalEntropy,NULL,NULL,
    CRYPTPROTECT_LOCAL_MACHINE | CRYPTPROTECT_UI_FORBIDDEN, &dataOut))

What do you do with dataOut to turn it into a string? I can't remember the exact details now, but I assume the constructor string is a BSTR. dataOut is a byte buffer, so you need to be very careful when converting it to a string, so you don't trip on embedded NUL characters, etc.

Could you update your question to include the conversion from the output buffer of CryptProtectData to string?