[Meesa]

I have Windows XP Pro Sp2, a little bit ago my computer all of the sudden just stopped downloading most things, a couple have been downloaded, but not much, I can't download my anti-virus update, nor hardly anything else, so it's NOT my browser! Nothing works with Firefox either! Anyways, so it's my OS.
Please note that my anti-virus (AVG free 8) finds no viruses, just spyware, and that is because the anti spyware is out of date.

Also, a little while ago I used a program to chage the logon screen, it compltly messed it up! now it takes like 20 min just to get to the logon screen and another 5 to 10 just to load everythig!

Any help would be appreciated, I'm pretty good with computers, so you can give me technicle stuff to try, and most simple stuff I've tried, but if you want, check to see if I've doen it.

System Restore isn't a possibility because it was turned off, and then didn't have enough room to recored the data (has been changed)

Thanks in advance!