Unexpected Alpha channel behavior in Premiere

Is there no way to interpret alphas as straight versus premultiplied in Premiere? Why do my transparent layers and clips with alpha channels display differently with a Black Video layer below them?
Background info:
I'm exporting my film to files with codecs that support alpha channels, not because I want an alpha in the result but because I need full RGB / 444 color coding for digital cinema theaters. I'm using ProRes444, Targa and PNG Image sequences to preserve as much quality as possible in my master exports.
I've discovered that there is no option to disable the alpha transparency in the Export Media step while preserving at least 10 bits per color channel (Trillions of colors in AE).
To solve this problem, I've had to add a "Black Video" clip to the first video track, underneath the film's content. When this is done, the pre-rendered text elements with alphas look different. They are movie trailer style text treatments that are light text over pure black. (I'm on my ipad right now and don't see a way to upload screen shots to show examples)
The result with the black video layer applied at the bottom is similar to the way QuickTime 7 displays straight alphas incorrectly. This problem occurs with both straight and premultiplied renders. The rendered text is from after effects and is stored using the animation codec.
I'm aware of how to work around this, by maintaining the alpha transparency in Premiere and then removing the alpha channel of my export by running it through After Effects, but that is a ridiculous, time consuming step.
I'm working with the GPU Mercury Engine on with a K5000 from NVIDIA. Can anyone explain this behavior? Is there no way to interpret alphas as straight versus premultiplied in Premiere? Why do my transparent layers display differently with a Black Video layer below them?
Here are the screen shots
UNDESIRED EFFECT using Black Video layer at bottom: Notice the fuzzy glow surrounding the text. This is happening with both straight and premultiplied renders.
INTENDED LOOK when composited over nothing: The glowing edges are displayed the same way in Premiere as in After Effects.

In my understanding, the reason 444 is indicated is because they are not RGB codecs. They simply sample the same amount of color as is possible in true RGB codecs. They still require a conversion from RGB to YUV for coding to a file, which almost always introduces a very slight shift in values, though usually imperceptible or acceptable. If the codec is truly RGB there is no need to indicate luminance vs color sampling.
...I think.
Again thank you for your awesome input! You've been a huge help here on my day off. :)

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http://www.rulli.org/~mravimo/seka/correct.jpg
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Welcome to the forum.
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Clean the media cache database via Edit | Preferences | Media
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Launch Pr and while it's launching, hold down the Alt + Shift keys until the Welcome screen appears. Alt resets your preferences and Shift resets the plug-in cache.
To address the other issues you say you've been having with Pr, you should start a different thread (or threads). Coming from other editors, there may be a difference in the way Pr does things that produce unexpected results that may be seen as bugs. More serious issues, such as crashes, can often be caused by 3rd-party hardware like AJA, Matrox or BlackMagic and the associated drivers. Outdated or incorrect drivers for audio and video cards can also cause problems. I recommend that you start troubleshooting those areas first.
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Adobe - Feature Request/Bug Report Form
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Thanks for your replies! So I'm not very good at explaining myself. I did export (and by export i mean, make movie by adding it to the render queue) the file as both of you are recommending. As a movie file, with an alpha channel, all one file. The reason I was trying to do it separate next was because it wasn't displaying properly that way.
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However,
THANK YOU for your replies and trys!!
(Oh yeah I should also mention that I did try, PSD sequence, Quicktime rgb+alpha, Lossless with alpha etc.. none of which seemed to work for what I was trying to do.)

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