Yahoo: Logging In

I have a Dell Inspiron B120 laptop, Windows XP. I'm using IE 7 and Opera 9.02. I am using McAfee anti-virus and privacy service. I'm using Microsoft's firewall. I use Ad-Aware as well.

I try to log in to Yahoo. I type in my Yahoo ID and my password. I'm taken to a page asking me to verify my password. My Yahoo ID is showing up in the box. I type in my password again. Taken to the same page, asking me to verify the password again. And again and again.

Changed the password but still going through the same thing.

Sometimes when I go to sign in, I'm taken back to the home page instead. I'm not signed in.

I've changed the password at least 5 times and waited 24 hours before trying to sign in again. I've contacted Yahoo three times and the last time, they assigned me another new password, which gave me the same results as before.

I don't understand what's going on. This may be unrelated, but when I downloaded the beta IE, there was one website that wouldn't display buttons on it. When I downloaded IE7, this problem disappeared, but it returned this week, same time as when I couldn't log into Yahoo. Maybe it's just coincidence, maybe not.

Also, hate to lump all the problems in one spot, but what if this is related? When I startup my computer, I get a message from windows installer saying it couldn't install word perfect 12. I click on "cancel" but it keeps coming back about 3-4 times, then finally disappears.

I'm sorry if I left anything out, hope I have given the necessary information. If anyone can help me figure this out, I would greatly appreciate it!