Although it looks like nothing more than a black Dell Streak with a white paint job, the white Streak is slightly different on the inside too. Yes, it still runs Android 1.6 out of the box and has the same components, but everything is not the same.
Ask anyone with a white Streak who tried to manually upgrade to Froyo how it went and then duck when the clenched fist comes speeding toward your face.
I don't know if the culprit has been identified yet but it doesn't really matter because the bottom line is that white AT&T-locked Streaks cannot be upgraded using the same method as black AT&T-locked Streaks. What they need instead is QDLTool, a repair tool that seems to have an incredibly high success rate of unbricking seemingly bricked Streaks and an even higher success rate of—wait for it—getting white Streaks from Android 1.6 directly to Android 2.2. From there, flashing DJ_Steve's 1.4.6 Froyo ROM (or even his new StreaksMI Alpha1 ROM) should be a breeze.
The QDLTool and a video tutorial on how to use it to get your white Streak properly Froyo-ed up can both be found at Streakdroid.[StreakSmart Forum | MoDaCo]