I just installed LP in Windows 7, 64 bit using IE 9. Starting IE 9 shows the LP toolbar and logo button, but just on the very first site. Switching to another site causes the icon to disappear forever, leaving an empty toolbar. If, on the first site where the icon is active, I click to open my vault, a page pops up then pops right out again, but I can make out that it says "an error occured no m_acccounts in CLPIE HomeCtrl" then I am directed to a page saying "Please enable LP add-on in IE 9." However, the LP add-ons are already enabled.
Importantly, LP seems to work fine (working on multiple sites) when I log on as an Administrator. The problem above only occurs when logged on as a standard user.