apt-get Size mismatch error

[Daniel R.]

When I try and run 'apt-get update' apt-get starts fetching all the file 
lists and stuff, but when it gets to reading the pkglist.update, 
srclist.update, pkglist.contrib, and srclist.contrib

It says "Failed to fetch [...URL of one of the above files...] Size mismatch"

I am not really sure what would cause this.  I tried using another mirror 
for the update section, but that did not help.  I am running YDL 3.0 on an 
old Beige box.

Yum seems to work fine for me, but I would like to know what is up with 
apt-get.

Any suggestions would be appreciated.

Thanks