Programs won't install

[*shiki]

I can't seem to install any programs or packages using the package manager or add/remove programs. It says the files cannot be downloaded because of a 404 file not found error. Is this a problem with my computer or is it a temporary issue with unbuntu archives? Or do I need to download packages to upgrade Hardy? I am new to linux and am currently thoroughly confused.

Any help is much apppreciated.

[Pumalite]

Check your connection, try a different Server. Finally, if that doesn't work, post:
cat /etc/apt/souces.list

[Bubba64]

Go to system-administration-software sources and make sure the CD is not ticked and you have repositopries on ticked, and follow Pumalites instructions to post your source list.