The mscpxl32.dll is Microsoft's Code Page Translator dll used by ODBC. Lookout's Citadel being an ODBC compliant database, tries to install/update this dll.
Looks like this dll is either in memory or is not accessible during the installation -- are you logged on as an Administrator (or with Administrator privileges) when installing Lookout?
You may want to shutdown as many programs and services as you can and then try installing.
Hope this helps.
Regards,
Khalid