Hi Sharon,
Sounds like you need the latest Windows Installer program to be installed. Click on the link below and select the WindowsInstaller-KB893803-v2-x86.exe
which is size 2.5mb. Click on the Download button at the side of this and save it to your computer. Once it has downloaded, double-click it to install it. Good luck!
http://www.microsoft.com/downloads/details.aspx?FamilyID=889482fc-5f56-4a38-b838-de776fd4138c&DisplayLang=en#filelist
Nigel
January 2009