first.html definition, relationships, removal:

The first.html file is an essential part of a particular parasite and therefore is responsible for the pest's malicious activity. Exact purposes of first.html depend on the related parasite's type and carried payload. Some threats can use first.html to serve annoying pop-up advertisements or store certain configuration settings, while others need it to corrupt files, steal user confidential information or run a spreading routine. In any case, DO NOT open this file!
The first.html file is installed and used by keylogger Activity Logger 2.0 and keylogger Activity Monitor 2002.
In some cases a presence of first.html does not mean that your system is infected. The file may actually belong to some fully legitimate applications and therefore must stay intact. If you are in doubt, please scan the first.html file using you regular spyware remover or antivirus program.