Problem with Update repository

[Bret Busby <bret@busby.net>]

Hello.

Recently, I have been getting an error message both from an update 
manager applet, and, in checking for system updates.

The error message is:

"
An internal error has occured and the operation has been aborted.
Error message:
Fetch failed: W:Failed to fetch 
http://http.us.debian.org/debian/dists/squeeze/updates/main/source/Sources.gz 
404  Not Found [IP: 199.6.12.70 80]
, E:Some index files failed to download, they have been ignored, or old 
ones used instead.
"

Please advise how to overcome this error.

I have tried to change the repository settings using
Synaptic -> Repositories -> Debian Software -> Download From
but it appears to not overcome the probem.

Thank you in anticipation.

--
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
  Chapter 28 of Book 1 of
  "The Hitchhiker's Guide to the Galaxy:
  A Trilogy In Four Parts",
  written by Douglas Adams,
  published by Pan Books, 1992
....................................................