Source and Program  preview look good,  AME renders linked aftereffects very poor

I have searched high and low but cant figure this out:
I have CS4 Master Suite installed on HPZ600 workstation Windows 7 Enterprise 64bit
Intel(R) Xeon(R) CPU X5550  @ 2.67GHz, 2661 Mhz, 4 Core(s), 4 Logical     6GB ram.
I created a 720p PremierPro (PP) sequence.  I added a “Black Video” then rightClick- replaced it with an aftereffects (AE) comp.  I added several screen captures to the AE file and animated a few graphics over the images.  When I jump back into PP the source preview (linked Comp) looks great, the Program preview looks good and when I Export media the 1st preview (still in PP) looks good.  Once it opens in Adobe Media Encoder the quality (mostly text on white background) looks terrible.
I have tried endless combinations of settings and options with no luck.  I render out the AE file and it looks great.  Import it into PP, looks great.  Send it to AME, looks like poop.  If I take the images (used in AE) and import them directly into PP I get a good export in AME but I need them in AF to animate.
If anyone has any info that might help I would be greatly appreciative.


No,  but that does seem to be a good indicator.  When the preview (AME) is  bad, the rendered video comes out bad.  When it is good, the video comes  out good. I just rendered this.  The preview showed about 1 second of  good quality and then the busted look (with linked AE only, video was  good).  This is a 1280 x 720 png in AE with no animation or effects.
The  linked AE is video2 in PP on top of 720p video in video1.  If I create a new  sequence and place (copy/paste from the old one) the linked AE alone it  previews and renders great.  Once I add the video (AE fades in over the  video) and have 2 720p elements, the AE will randomly look bad.
Do you think it could be a RAM issue?
Here is an example:  This is a rendered WMV about 20 seconds in.
Here is the same WMV 21 seconds in.  It is the same image in AE.  This quality shift was also identical in the AME window.
thank you for your time and info, I appreciate it.