Today we had a weird error on our SharePoint 2010 production farm: clicking on help got the "help content cannot be displayed" error for all normal sites, even though it worked perfectly well in Central Admin. The same applied to Site Settings>Help Settings for the site-collection, it worked in Central Admin, but not in any other site. In addition, the 'SharePoint Foundation Search' service was running on one WFE server.
First I checked all settings in KB939313 without that fixing the problem, then I checked the log files and found this access denied error for our site's app-pool account:
SqlError: 'The EXECUTE permission was denied on the object 'proc_EnumResourcesAtScope', database 'SharePoint_AdminContent_ABBAef34-7603-4da5-823a-43ee1327ABBA', schema 'dbo'.'
Before embarking on changing any database rights, we decided to test with an English site just in case, as all our custom site definitions are in Norwegian. Lo and behold - help worked for the new team-site; and what's more, suddenly help was working for all our existing Norwegian LCID 1044 sites also. Go figure...
[UPDATE] See the comments for tips on granting execute rights on the sprocs listed in the ULS to fix this problem once and for all - even beyond IISRESET.