Will not install (among other oddities)

When I've chucked Category into the modules folder and open the modules page, I get the following error log beneath the blurb (before the functions):

• warning: parse_ini_file(modules/category.1/contrib/cac_lite/cac_lite.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/category.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/contrib/category_bulkedit/category_bulkedit.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/category_display/category_display.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/category_export/category_export.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/category_legacy/category_legacy.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/category_menu/category_menu.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/contrib/category_outliner/category_outliner.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/contrib/category_pathauto/category_pathauto.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/contrib/category_transform/category_transform.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.
• warning: parse_ini_file(modules/category.1/contrib/category_views/category_views.info) [function.parse-ini-file]: failed to open stream: No such file or directory in /var/www/sites/drupal/includes/module.inc on line 195.

...However this is just a symptom. Another one is that the available modules for install have no label text nodes. I can only tell they are the Category modules by looking at the source of the tick boxes.

When I use the source view to work out which boxes I want to tick, and attempt to install these, I get the following error:

Fatal error: require_once() [function.require]: Failed opening required './modules/category.1/category.install' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/sites/drupal/includes/install.inc on line 726