Go here; http://www.gt500.org/malwarebytes/database.jsp and download the latest database. Save it to whatever you are using to go between the pc's, then run the update on the infected pc.
Re-run MBAM again doing a full scan and remove what is found.
Reboot the machine and post a new hijackthis log and the MBAM log.
Let me know if you can get online.