An issue was brought to my attention today at work where certain users were unable to open Office files (specifically Excel) from Internet Explorer 7.

The user would click on a button which simply generated an inline JS call to open a pop-up pointing to the .xlsx file on the server. IE would open the pop-up and then shortly thereafter the pop-up would disappear without the file ever opening.

I tweaked the security settings in the users browser...added the site to the list of trusted sites and lowered the security settings to Medium-Low. This allowed IE to at least prompt with the Save or Open message. Clicking either open resulted in "Internet Explorer Could Not Open the Site...".

Perturbed, I retreated back to Geek Central (aka my desk) and modified my application such that instead of simply pointing the browser to the file and now used Response.TransmitFile() to stream it to the browser instead. I thought to myself "this is perfect, it has to work!!!". Alas, no luck.

Bewildered and confused and returned to the lone users computer and started looking around the various IE options. I stumbled upon "Clear SSL State" under the "Content" tab. This appears to clear out all SSL certificates on the client forcing it to refresh. Doing this in concert with resetting the security levels for all zones back to their defaults seemed to do the trick.