Try reinstalling SP3 if you can. Go to Control Panel, Add/Remove Programs, and then select Windows XP Service Pack 3 (or something similar) and uninstall it. You may have to download the service pack again, and the way your machine is behaving, possibly with another computer. If you don't have another machine, you may be able to boot into Safe Mode with Networking to connect to the Internet without these errors (to boot into Safe Mode, press F8 before you get any Windows screens when your machine is starting. You may have to try it a few times to press F8 at the right time.)
Also, if you can, post a HijackThis log. I doubt that this is malware-related, but it will help us tell what software you have running that could be a part of this problem (the above-mentioned BricoPacks, AVG, and some others are known to be involved with this error). To download HijackThis, go to
http://www.filehippo.com/download_hijackthis/. Install it, restart, and then run the program. Select the option that allows you to create a log, and then post it here.