IE8 is hardly new. It's been around for 4 years now. (The latest version is IE10, with IE11 expected to be provided with the update to Windows 8).
It's far more likely that Windows has lost the 'file association' which tells it which program should be used to open a particular file type. Save one of the files to your hard drive, then right-click on it. Select 'Open with' and 'Choose program'. (It's important to select 'Choose program', even if you can immediately see the program you want to use in the list which is initially offered to you). Then click on the required program (e.g. 'Adobe Reader', or similar, if it's a PDF file) AND (most importantly) put a tick alongside 'Always open this type of file with this program', before clicking on 'OK'.
Hopefully your computer will then know how to open downloaded files.