Thanks for the feedback but its not the solution I was looking for. Its not just the W3 Total Cache plugin that causes the 500 error but any changes to the .htaccess file in relation to cache.
This is the code I added to the .htaccess file
## EXPIRES CACHING ##
<IfModule mod_expires.c>
ExpiresActive On
ExpiresByType image/jpg “access 1 year”
ExpiresByType image/jpeg “access 1 year”
ExpiresByType image/gif “access 1 year”
ExpiresByType image/png “access 1 year”
ExpiresByType text/css “access 1 month”
ExpiresByType text/html “access 1 month”
ExpiresByType application/pdf “access 1 month”
ExpiresByType text/x-javascript “access 1 month”
ExpiresByType application/x-shockwave-flash “access 1 month”
ExpiresByType image/x-icon “access 1 year”
ExpiresDefault “access 1 month”
</IfModule>
## EXPIRES CACHING ##
I want to be able to speed up the site without it giving me a 500 error everytime. Do you have any idea why I am receiving this error?