Sometimes users install popup blocking programs to prevent annoying advertising from popping up in new windows while browsing the internet. Unfortunately this prevents CATS from functioning because CATS needs to be able to open new windows to display download dialogues and dynamic forms. If you want to use CATS, you must enable the use of popups for the CATS site.
Depending on the particular popup blocking software you are using you may be able to specify that the CATS site is allowed to popup windows. If you cannot do this and you still wish to access the CATS system then you must temporarily disable or uninstall your popup blocker software while you use the CATS site.