I have a number of users that I support that cannot open a PDF file downloaded from a training website (external website, not intranet). Using IE8 they get a flash of status bar activity and then nothing. On my computer with IE9 I have no issues opening them at all. I've changed all the security, privacy, content and advanced settings to match what I see in my internet options, but that hasn't helped. I can't figure out what has changed between IE8 and IE9 that causes this. Adobe Reader 9 is installed on all machines. Firefox 10.0.2 will open the files also, but has issues with some of our propriety software so we can't use it as a workaround unfortunately. I've also added the websites to the trusted list, but that didn't help either. Any ideas?