apt problem?

["jeb" <jeb@starflight.com>]

I've used dselect/apt for a long time to update my debian 
distribution. For the last several days when I tried to update I get 
the following message.

Updating package file cache...
E: Line 3 in package file
/var/state/apt/lists/ftp.debian.org_debian_dists_potat
o_main_binary-i386_Packages is too long.(2)

I tried getting distribution from different sites -- no luck.

I looked at the file mentioned. Line 3 is a normal line.

I did apt-get clean to start over.

I get the same message regardless of whether I download main, 
non-free, or contrib sections of the dist. I tried them all 
separately -- same result.

The message seems unhelpful to me.  Does anyone have a clue as to 
what's happening and how to fix it? 
  
I'm not sure what version of apt I have. That's one of things I was 
trying to upgrade.

Thanks,

JEB