Unable to extract /usr/local/lib/php/drush/lib/drush-library-x. Unknown archive format.

I've been able to install drush on my vps account at inmotionhosting, but when I try to run any drush command (status, help, etc), I get the error above (drupal-library-8NUMBERS depending on the command).

I thought it might be permissions in the drush/lib directory, but after setting them to 777 still wouldn't run the command.

Then I found this in drush.inc :

function drush_tarball_extract($path, $destination = FALSE, $listing = FALSE) {
  // Check if tarball is supported.
  if (!drush_file_is_tarball($path)) {
    return drush_set_error('TARBALL_EXTRACT_UNKNOWN_FORMAT', dt('Unable to extract !path. Unknown archive format.', array('!path' => $path)));
  }

Not sure why that error would be thrown. I just did the pear install this morning. I doubt it is a bug, but wonder if anyone might have some ideas for me as to where I should look to get drush working.

Thanks.