Who set the Admin Policies on your machine (if not you)?
W7Home premium (AMD 64) UAC as shipped, just installs after the standard screen dimming question-password.
Your security suite may be blocking.
BTW it really helps if you paste the Exact error message into a spoiler (red X eye).
Using: Ubuntu(32 bit):Oneric,Precise and XPpro SP3, W7HP(64)- - Libre Office w/Writer2EPUB