If you have ever been involved in fixing computers then you will know that windows installer is disabled by default in Windows Safe mode meaning that you cant install or remove programs.
You can enable it though by doing the following :-
1) Boot Into Safe Mode
2) Start, Run, Regedit
3) Navigate to the following key
4) Right click on the Minimal folder, left click on new, key.
5) Type in msiserver, hit enter
6) Click on the newly created msiserver folder. On the right hand side you will have (Default) and (Value not set)
7) Double click on (Default) and type in the value Service. Then click ok.
Now close the registry editor and click start, run.
net start "Windows Installer"
You should now be able to go into add / remove programs and install stuff.