So you wrote this real cool web application that used automatic pop-up windows in interesting ways. Unfortunately, XP SP2 was installed on people's machines and your application doesn't work. What to do?
First understand Pop-up Blocker:
User perspective information here and here.
Detailed TechNet intro is here as a topic of a larger intro to XP SP2.
Upshot is that if your program uses program-driven pop-ups you should rewrite your application to pop up in response to user input, which is not blocked. If you can't do that, you can set the following registry setting to allow pop-ups from your server.
HKEY_CURRENT_USER \Software\Microsoft \Internet Explorer \New Windows\Allow
Here is more information on the pop-up blocker registry settings.
Finally, if you are using AD to control the desktop machine, such as for a corporate intranet application, for example, you can make changes to your Active Directory Group Policy. Go to this link, download the spreadsheet and search for “pop-up” The policy names “Use Pop-up Blocker” and “Pop-up allow list” are good places to start. More info here.