Ramfade you mentioned you have removed the preferences and cache. Can you please confirm if you have completed the steps listed in Solution 1 of Troubleshoot Adobe Download Assistant - http://helpx.adobe.com/creative-suite/kb/troubleshoot-download-assistant.html#main_Solutio n_1.
I ran into this issue when a download was interrupted unexpectedly. Once I completed the steps in solution 1 and reinitiated the download I was able to download the trial successfully.
You might also want to try a wired connection or a different Internet connection while trying to download. Perhaps there is a server between you and the download server which is causing your difficulties at the moment.
Jeff - Thanks for trying to help. I did complete step 1 with no change in symptoms. I kept getting the SAME CRC CHECKSUM (in Disk Utility) with each download:
$68976E38, expected $811480B9
The solution that I couldn't find in the forums was to type this command in Terminal:
> defaults write com.apple.frameworks.diskimages skip-verify -bool YES
That allowed me to mount the disk image and install Photoshop without a hitch.
Thanks to Sumi in Live Chat for this command!
I know this was a few months back, but do you mind sharing how you entered the command in the Terminal? I've never done that before and find myself facing the same problem! Thanks so much in advance.