UR's built-in popup blocker pre-dates the one IE added in Windows XP SP2. It can only block some popup methods.
It turns out that the IE popup blocker can be also enabled in an embedded browser instance via a registry setting, as described here:
http://msdn.microsoft.com/library/de...pSp2Compat.asp (Pop-up Blocker section).
Importing the attached .reg file and restarting UR will cause UR's internal IE browser to honor popup blocking if enabled in IE proper. The documentation implies that this is specific to Windows XP SP2, so it may or may not work on earlier Windows releases.