I have the identical problem starting Apache on Windows7; new beta of xampp control says "Possible problem: port 80 in use by 'system' "; I have disabled IIS and it is clearly not running. I do not have VMWare installed, so I assume that the later suggestions are not relevant. Any other ideas?
By the way - I previously had Microsoft Express Web Development System installed, and it automatically started IIS. I ended up uninstalling the MS Web Dev system, and IIS no longer automatically runs. Any ideas on what else is using port 80 and how I can prevent it? Earlier suggestion of checking run Apache as a service on the xampp monitor and rebooting did not work.