There is a critical remark/discussion about certain event-errors in windows being logged/generated as a result of a recent piriform update, if you check the Application tab "SEARCH" box for cleaning. I am having the EXACT same problems described in this link, and I will see if this still occurs after unchecking meanwhile I invite Piriform support to investigate this issue thoroughly.
MORE: 1811 errors being generated:
Windows (3084) Windows: Error -1811 occurred while opening logfile
Urgent? It's been hanging around since Sept 2011. According to the response from a MS staff member in that thread the cause is a problem with Windows Indexing. Unchecking the Search box in CC may stop the errors, but is the underlying problem with Win Index? (I can't test as I don't have a Search box in Applications, presumably as I have disabled Indexing, or I'm not on Win7, or both.