Computer problems, I can't download anything

Okay, so lately I've been having computer problems.
It's not letting me download ANYTHING. Any help, please?
And I've been trying to get flash player so I can watch youtube videos and everything.
And there's this site called 'Habbo' that my little cousin plays, and she cant go on it anymore. And she absolutely LOVED that site, and I hate seeing her sad. It keeps saying all kinds of stuff, like, 'Check and make sure your temp. folder is valid' or, 'This file is in use of another ... etc.' and I know it needs Flash Player, but like I said before, its not letting me download anything. And even when I DID have flash player, sometimes it said, 'Your ActiveX controls may be turned off. Cannot go to site.'
And all kinds of stuff.
How can I fix this?

re-install the operating system

how? :S

this may sound a little complicated but set your primary boot device to your cd rom drive which contains your operationg system cd like xp cd then when you turn it on press enter to boot from disk it will come up with a whole bunch of screens showing your partion drives... oh screw it download a tutorial of the net or get a computer place to repair it for around 40 bucks!

you have your cookies set to high for some reason. right click on your internet explore the big e and then go to privice and set your cookies to low. Hit apply and then try it again.