Oddly I have had no issues in importing Prores files into AE CS4 however when I attempt to do so in AE CS5 I get an error which reads as "unreadable format". I have scoured search results and updated Quicktime on my PC. Any help is appreciated.
i suspect the issue is with cs5... cs5 is 64-bit while cs4 and quicktime are 32-bit. i know adobe has a background process to handle the 64-bit/32-bit translation with quicktime, but it may be having issues...
do you have the latest version of cs5? and have you tried rebooting your machine?
if you can answer yes to both of those, do you have any issues with other quicktime files encoded with other codecs, like lossless animation, photo-jpeg, etc?