I'm not sure if you're using XP Home, or XP Media edition, but both will behave the same way. You're computer is having problems with spyware on it. This problem will usually occur after running a spyware cleanup program like Adaware or Spybot. Both of these program are terriffic and I endorse them, they are not to blame. Both Norton and McAfee are known for causing browsing problems, but the issues you have here is a result of damage that was done to internet explorer. You'll notice you can go to any website, except for those that are password protected. You'll also find that the windows update wesite won't work, either. If you're using a router, it's best to remove any and all firewall software from your computer. The firewall is handled by the router, which is your frontline connection to the internet. If you are connected with this PC being the only one connected directly to the internet, simply enable the windows firewall and remove McAfee entirely. For antivirus, I recommend Grisoft AVG free edition. You can download it here for free.
http://www.free.grisoft.com. It's certified for 100% detection, and will likely find viruses on your machine that McAfee doesn't catch (and for a price!). Now, on to fixing your current problem. On your machine, click START and RUN. At the prompt, enter each of these lines below. Click OK after each one. It will reregister the DLL's necessary for Internet Explorer to work properly. After you get IE working, install AVG and scan for viruses. (It's easiest to copy and paste them, like I did here)regsvr32 jscript.dllregsvr32 Softpub.dllregsvr32 Wintrust.dllregsvr32 Initpki.dllregsvr32 Dssenh.dllregsvr32 Rsaenh.dllregsvr32 Gpkcsp.dllregsvr32 Sccbase.dllregsvr32 Slbcsp.dllregsvr32 Mssip32.dllregsvr32 Cryptdlg.dllDon't neglect to uninstall McAfee, that computer will run faster without it.-Randy PetersonMouseworks Computer Service