Oracle Database Express Edition (XE)

I'm encountering a problem that's come up before, as I look through the forum archives. The replies are out there on what to do, but I guess I still don't get the solution.

The os is Windows XP. Oracle XE is downloaded from the Oracle site, then installed. I go to the Database Home Page, put in username (system) and password, then the fields clear and I'm back to the starting point. Zone Alarm Pro is my firewall and virus/spyware security. I can go to a dos window and login directly via sqlplus with system/password, so there are no problems there.

Ran the equivalent on my laptop, which has Norton Internet Security. Everything went just fine, and I got in through the home page.

So, what should I do to get around this problem on my main pc with the Zone Alarm Pro? Thank you.