title: Magento error after trying to enable System >Tools> Compilation
body: <p>I am on Magento 1.7 CE, &amp; to speed up the site, went to System >Tools> Compilation and hit Enable. And my site is down!</p>
  
  <p>First, which file on the server do I change to fix this?
  Second, is it true that you do not Enable this ever, but rather just click on 'Run Compilation Process'? And if so, how often?</p>
  
  <p>Thanks.
  -TM</p>