Microsoft xp home page icons wont open with left click

My win. XP home page icons will not open with the usual one left click of the mouse. They will open if I right click once and then click on the word "open". The only icon that works by a single left click is the "Internet Explorer". The only other trouble with my computer is that MS Office 2010 will not open at all. Error message says "Window Installer Service could not be Accessed".

Thanks for any help David Ebbighausen