We reviewed 188.8.131.52 build of Kaspersky Internet Security 2012 Beta earlier and it had a lot of issues on my configuration, thankfully newer builds are getting released fast fixing bugs reported by users. However, when you try to install a newer build on an existing installation the KIS 2012 BETA installer refuses to install the application displaying "Internal Error 2771" error, after trying things here and there I was able to install the new build.
Internal Error 2771, SandboxFeature
Internal Error 2771, WholeProductFeature
To get past these errors all you need to do is to uninstall the previous build completely and reinstall using the newer build setup.