Id say reinstall window too but can you back up all your data onto cd first. Its probably not necesary but best to be on the safe side.
Your TCP/IP settings are used to connect to the Internet. Has anyone been messing about with any of your settings or anything? Does it give you any further information on what the Windows protection error is? Did you have uptodate virus software on your machine as poss could be a virus.
Did the microsoft message come in a pop-up? If so then it was probably a virus, not a genuine microsoft upgrade. Sure I have seen a warning about this, will do a quick search and see if I can find some info.
Hope this doesnt sound bad but when you say you cant use your cd do you mean you cant see it at all when you go to My Computer? If you click on My Computer it will give you a list of drives lie c: which is your hard drive and A: for floppy etc. Sorry if Im being a bit basic here. Cos if you cant use your cd its gonna be a bit of a bugger to fix
I never download patches/updates when stuff pops up on my screen. Every couple of months I go to the microsoft home page and download anything I think I need from there. Safer - plus you only download what you really need, a lot of the stuff in patches isn't relevant to 80% of users.
Aimsmum - I am very wary of anything that appears when I access the internet unless I have put the address in myself! Unfortunately the hackers/virus writers are getting so clever - combined with me getting very paranoid about computer security
Unfortunately I don't really know enough to help you. I still think it might be a virus but only because I have never heard of it going direct to the Microsoft homepage like that before - I get the icon flashing on my toolbar when it is a genuine update.