I would be suspicious of third-party software, especially antivirus software.
Interesting. I hadn't considered that. You think that would be it even though plenty of other software has installed just fine? The only antivirus I have is security essentials.
You think that would be it even though plenty of other software has installed just fine?
I'm not saying it is necessarily the cause, but just my best guess as to the cause. It should be easy enough to test though!
There have been two similar reports in the last year or so that I can find, and it looks like an installer problem when CS3 was previously installed (did you have CS3 or CS4 installed and remove it?).
What seems to be happening is that the type support files aren't properly written to the correct location, and it wasn't entirely clear to me this morning if either previous report was finally resolved. That said, I'd do the following:
Uninstall using Windows control panel.
Run the CS5 clean tool: Resolve installation problems with CS5 Cleaner Tool
Run MSconfig and trun off non-essential startups, especially antivirus, browser helpers and toolbars, iTunes, and instant messengers.
Reinstall any versions you want, in chronological order. Be sure InDesign is installed into the Program Files (x86) folder (this should happen automatically if you leave the default location).
Run MSconfig again and restore normal startup.