title: Magento site keeps crashing inconsistently
body: <p>My magento site has started crashing. Recently while accessing the site mostly shows the following error message</p>
  
  <pre><code>There has been an error processing your request  
  Exception printing is disabled by default for security reasons.
  Error log record number: xxxxxxxxxxxx
  </code></pre>
  
  <p>After refreshing the site several times the normal page is displayed again.</p>
  
  <p>The error report written to <code>var/reports/&lt;error log record numer&gt;</code> begins as follows:</p>
  
  <pre><code>a:5:{i:0;s:82:"Category Products Index process is working now. Please try run this process later.";i:1;s:2099:"#0 /home/krishbal/public_html/app/code/core/Mage/Index/Model/Process.php(162): Mage::throwException('Category Produc...')
  </code></pre>
  
  <p>Has anybody stumbled upon this before?</p>