unable to start udate or synapitc manager could not initialise the package information

[dbolton]

unable to start either the update manager or the synaptic package mananger
  after a fresh install of 7.04 and doing the updates offered . on the restart i went to open synaptic manager, i recived this message.

could not initialise the package information
an unresolvedable problem occurred while initialising the package information
please report this bug against the "update-manager" package and include the following error message:
"E:Read error - read (5 input/output error), E:the packeage list or status file could not be parsed or opened"
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
I'm getting the same error. I haven't installed or changed the system since the last update I ran which was about 5 days ago (Today being the 20th June 2007).

I've tried looking at my status file and my sources.list file and there doesn't seem to be any problems with either file.