Magento

Installed magento-1.0.19870.tar.gz on linux fc7, apache 2.2.8. Had Magento working and began poking around some of the admin screens. 
Now all I get is the error 404 page. No I don’t know what was changed. Perhaps something in the db was changed. I narrowed it down to app/Mage.php lines

441 catch (Mage_Core_Model_Store_Exception $e) {
442 $baseUrl = rtrim(dirname($_SERVER[’SCRIPT_NAME’]), ‘/’);
443 header(’Location: ‘ . $baseUrl.’/404/’);
444 die();

so I commented out that catch so that the next catch can print out the following trace:

Trace:
#0 /var/www/virtuals/mark/httpdocs/magento/app/code/core/Mage/Core/Model/App.php(541): Mage_Core_Model_App->throwStoreException()
#1 /var/www/virtuals/mark/httpdocs/magento/app/Mage.php(192): Mage_Core_Model_App->getStore(NULL)
#2 /var/www/virtuals/mark/httpdocs/magento/app/Mage.php(197): Mage::getStoreConfig(’web/url/use_sto...’, NULL)
#3 /var/www/virtuals/mark/httpdocs/magento/app/code/core/Mage/Core/Controller/Request/Http.php(110): Mage::getStoreConfigFlag(’web/url/use_sto...’)
#4 /var/www/virtuals/mark/httpdocs/magento/app/code/core/Mage/Core/Model/App.php(233): Mage_Core_Controller_Request_Http->setPathInfo()
#5 /var/www/virtuals/mark/httpdocs/magento/app/Mage.php(404): Mage_Core_Model_App->init(’’, ‘store’, Array)
#6 /var/www/virtuals/mark/httpdocs/magento/app/Mage.php(426): Mage::app(’’, ‘store’, Array)
#7 /var/www/virtuals/mark/httpdocs/magento/index.php(40): Mage::run()
#8 {main}

I’d like to correct this without reinstalling from scratch.  Any clues appreciated.

Thanks,
Mike