Pop-up requesting me to download a file when

[Gillonline]

I am at my wits end! Everytime I access Outlook, I get repeated pop-ups asking me to download a file from c:\users\appdata\local\microsoft\windows....... folder. (I can't see the rest of the filepath but think it's temporary internet files) I was using Firefox as default browser and the file type for the spurious downoad was Mozilla - so I uninstalled firefox and reinstalled it but to no avail. So, I set IE as my default browser - and now the pop up has changed to file type HTML document.
Anyone any ideas?