Thank you for your post.
You mentioned Internet Explorer "7 & 8" are the only browsers encountering this problem. Can you provide any more information about the file in the Container field? That is, what type is it? PDF? Word Document? Have you tried a button to "Export Field Contents"?
Any other information you can provide (Internet Explorer preferences, database file, etc.) may be helpful in determining why the file cannot be downloaded.
Sorry for the slow reply - I was side tracked onto other more urgent enhancements to the system. I understand our customer's customers are having trouble downloading files with I.E. with a mix of versions between 7 & 8 (and possibly 6 & 9).
I have tested using Windows XP on VMWare running IE 8.0.6001.18702 and I have tried it with all the settings as default, I have also tried turning all the security settings down to the minimum and adding the URL of the IWP site to my trusted sites.
The Export Field Contents script step is not IWP compatible... In addition to this, whilst googling I found this thread on FM Forums, that suggests the Export Field Contents script step could be causing the issues. So I have not tried an Export Field Contents button and I have double checked that the container itself is not a button.
The current version of FileMaker Server is: 220.127.116.11 (Windows Server) - I have not yet tried the update to version 11.03, is it possible this could fix the issue?