"3rd party modules"
It has been reported there is a community extension by the name of the "compiler module" for Magento, if you use this extension please disable it while installing the VAF extension.
It has been reported the sqlI reverse cross selling extension tries to override the same files as us. Use our patch
until Varien fixes.
Always backup all of your files & data before making major changes to your store such as installing any Magento modules!