Why can't I get java to download?

I was trying to update my java and had to delete the older version. When I try to download (after deleting the old version) I get an error message that says-“Error 25099:Unzipping Core Files Failed.” Now I have gone to the website and completed the steps there to fix the problem, yet I’m still getting the same message. Second question! Why won’t my PC restore itself to an earlier date? I decided to just go back to an earlier date before all this happened and (3 times) I’ve gotten the same message-“An unknown error caused the system restore to fail”. Here’s my info-Windows Vista Home Premium 32 bit. I’ve tried the download with Firefox 3.5 and IE8. Please help before I throw this thing out a window! I have plenty of disk space so that’s not the problem!