windows installer on vista 64bit

Question

Hi, i can not seem to get my windows installer to operate, for an example i can not open adobe 9.1 or uninstall it. i have a windows vista 64bit operating system. for an example if i try to open a pdf file i get the following error "An internal error accurred". and if i try to uninstall adobe i get the following error message "The windows installer service could not be accessed. This can occur if the windows installer is not correctly installed. Contact your support personnel for assistance".  i tried installing windows installer 4.5 but that did not help. please help.