One thing that might be going on here is this…
1. You send clips from PrP to AE via dynamic link
2. You work on moves in AE.
3. You switch back to PrP. In order to view all your DL clips you most likely need to render them in PrP.
PrP is set to MPEG I frame as the default setting for rendering Preview files. These are a a very low resolution to allow quick rendering. They do not affect the process of Exporting your time line, but are just a reference to look at while editing.
This could be causing the resolution change you are noticing.
Tom Daigon
PrP / After Effects Editor
http://www.hdshotsandcuts.com
https://www.youtube.com/watch?v=DxPrG3WUyz8
(Best viewed at 1080P and full screen)
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