That's odd, the HidePriceUntilCart should, by itself, mask the price.
Are you using modified XML Packages on the pages that display that information?
It could be that the developer who did the mods left off honoring those to be toggled, which would require modifying the XML package to fix.
I just verified against the stock aspdnsf_ProductInfo and aspdnsf_GetProducts stored procedures, and both should be returning the HidePriceUntilCart value for each product. That means that your XML package(s) probably isn't set up to do anything with that value.
Take a peak into the entity-package that is displaying the price and do Find for "HidePriceUntilCart", if you don't come back with anything, then that's your culprit.
Follow-up question, is the price continuing to display across all your pages, or is it just on a few? If not all of them, then which entity-pages are showing it?