Cannot install Java.why?

I have a Acer Aspire laptop with Xp Prof on it. I have had it new for about 2 months now and have tried to put java on it and cant. I have disabled norton and firewall and still cant. When we first got it to took about 2 days and it finally installed, but we unistalled it cause a program was not working so we uninstalled it and then went to reinstall and cant. It will download fine but when you go to install part it stops witht the following error...."this installation package could not be open, verify the package exsists and that you can acess it or contact the vender to verify this package exisit."

What does this mean? How come I downloaded it that first time after trying for a bit, but now I cant at all?

[729 byte] By [dalefana] at [2007-11-26 19:44:29]