I verified on my Mac 10.7.4, in developer edition I don’t see any issues installing Update 4. I was able to install the Update successfully.
Well, I'm not sure if this is an issue on MacOS as well, but even if you download the Windows 64-bit ColdFusion 10 Developer today (which I actually did), it has a bug in it that requires you to install a Mandatory Update before you can then install the Updates in the CF ACP. Have you checked on this?
CF Mandatory Update Page > http://helpx.adobe.com/coldfusion/kb/coldfusion-10-mandatory-update.html
I installed the mandatory update OK before trying to get the other updates. If I download the updates individually I can install them via the command line, just can't get them via the auto update. Thanks
This same error also happens on a Win 2003 server upgraded from Cold Fusion 9 to 10.
This server had Cold Fusion 9 installed, and then I upgrade to Cold Fusion 10. The migration was successful, and then I installed the mandatory update. After the mandatory update, when a user logs in to the Administrator, they get a message saying "Error invoking CFC /CFIDE/administrator/updates/download.cfc - Content is now allowed in the prolog" This machine was also missing the /cfusion/hf-updates folder, if that's of any help.
On my local Windows 7 machine, I installed Cold Fusion 10 on top of Cold Fusion 9. As hotfixes were released, I installed them. CUrrently, my machine doesn't have this problem, so it seems to be something that the mandatory hotfix did to unpatched systems as opposed to patched systems.