After the HC installation all sites stop responding.

Hi,
 
After the HC installation in a windows 2003 server all sites stop responding.
Even with the hc removal the issues continue.
How to resolve that?
 
Regards,

HC installation has nothing to do with existing website, The only problem might come if websites are running in .net version. As HC remove .net mapping from root of IIS which is recommended otherwise it will enable by default with every website.