error with apt-get update

[Vijaya S <vijaya@picopeta.com>]

Hi all,
When i try to do apt-get update i get the following error:-
99% [1 Packages gzip 9994240]
gzip: stdin: invalid compressed data--crc error

gzip: stdin: invalid compressed data--length error
Err http://xyz.com unstable/main Packages
  Sub-process gzip returned an error code (1)
Fetched 3183kB in 2s (1304kB/s)
Failed to fetch
http://xyz.com/debian/dists/unstable/main/binary-i386/Packages.gz
Sub-process gzip returned an error code (1)
Reading Package Lists... Done
W: Couldn't stat source package list http://xyz.com unstable/main
Packages
(/var/lib/apt/lists/xyz.com_debian_dists_unstable_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: Couldn't stat source package list http://xyz.com unstable/main
Packages
(/var/lib/apt/lists/xyz.com_debian_dists_unstable_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: You may want to run apt-get update to correct these problems
E: Some index files failed to download, they have been ignored, or old
ones used instead.

How do i fix it?

Regards,
Vijaya