why won't the install wizard start up?

I am not sure if this is the right forum to address my question but it does have to do with CAVS ( also personal firewall) , so here goes…

I have been having trouble installing CAVS and the personal firewall on my Windows 2K Pro OS. While I can download the file and save it, when I try to install it, the download wizard never starts. I get the window to close all applications and when I press OK the box disappears but the wizard never starts. I have even gone into task manager and endded all applications. I have been able to install BOClean. I have had problems with other programs that I have tried to install. I worked for a company until about a year ago, whose computer IT guy had once boasted to me that he could get into anyones computer. Since I worked out of my home office 2 hours from headquarters, and frequently had to share files, attachments etc. I often wondered if they had planted a monitor. When I started having problems installing programs, I started looking around my computer. From the control panel, I went to Computer management, Local Users and Groups, Groups, and then Administrators. Under Administrators, I found four administrators listed that I never set up. They are \S-1-5-21-855903348-76970788-310601177-1005, \S-1-5-21-855903348-76970788-310601177-1020, \S-1-5-21-855903348-76970788-310601177-1038 and \S-1-5-21-855903348-76970788-310601177-500. They do not show up when I go to the Users and Passwords section in Control Panel. Not knowing what they are, I did not want to remove them, but I am concerned that someone may have created a back door to allow them admin rights on my computer.

So my questions are:

  1. If this is the wrong forum to address my questions, could you recommend the proper forum?
  2. Are these administrators a normal part of Windows 2K Pro?
  3. If someone gained control over my computer, could they have made changes to my Config file, Install Shield, register or what ever to prevent your product from installing?
  4. Is there a way to log what my computer is doing, so that I can find out why the install wizard just terminates?

Thanks in advance for your suggestions.