When i try to install at the bottom right it says "Configuring Windows Installer" Then i get an error: 1607: Unable to Install InstallShield Scripting Runtime

I had the same problem but it i found the solution at windows help online. heres the link http://support.microsoft.com/default.aspx?scid=kb;en-us;315346

I had the same problem and found it was nothing to do with windows installer. i had previously installed doom3 but after installing xp sp2 everytime i tryed to load doom3 i would get a BSOD (blue screen of death).Removing doom3 and reinstalling it resulted in the error you mention. To fix it do this :- 1. open windows explorer and goto tools/folder options/view ,select box that says show hidden files and folders and apply changes. 2. open C:\Documents and Settings\USERNAME\Local Settings\Temp\ - where username is the name your logged into your computer with. Delete everything in the temp folder. If it complains that it cant delete somthing restart your computer and try again. 3. goto startmenu/run type regedit and press return.Delete these keys:- HKEY_CURRENT_USER\Software\DOOMRadiant HKEY_CURRENT_USER\Software\id HKEY_LOCAL_MACHINE\SOFTWARE\id HKEY_USERS\S-1-5-21-343818398-1500820517-839522115-1003\Software\DOOMRadiant HKEY_USERS\S-1-5-21-343818398-1500820517-839522115-1003\Software\id 4. restart your computer and install doom3 enjoy :).