windows installer error(s)

Recently I've been having trouble with the windows installer. There are a couple of applications that when I try to install I am presented with this message: "Error 1324: The folder path 'Program Files' contains an invalid character." There is also a messge that says: "This isntallation package could not be opened." I have searched extensively for a solution to these problems and have tried to update Windows installer, but that didn't work. I understand that these problems can be solved by changing the registry, either adding or changing the value of a key, only I don't know where or what to change. Any help would be appreciated.

 

Are you using the latest version Windows Installer 3.1
If not, here's the download link:
http://www.softwarepatch.com/windows/wininstallnt.html

 

I had similar program a while ago - it turned out to be webwasher running in the background.