Access to file write.lock in ASP.NET web application writing a Lucene search index

I created an ASP.NET application that uses Lucene for searching my web pages. Locally, everything works fine, but when I deploy it to the IIS server, the code that generates the write.lock file during the creation of the index, gives the following error:
Access to the path ‘C:inetpubwwwrootGcsWebOnlineHelpwrite.lock’ is denied.