register java plugin for IE could fail on vista x64 during install of FX 2.1

Please refer to the following JIRA issue for more details:

    http://javafx-jira.kenai.com/browse/RT-19956

Basic reproduction steps:
1) install 7u4 b15
2) install FX 2.1 b15

In a REG*.tmp file in the "temp" directory, the following statements are there if the bug is reproduced:

UpdateRegistryFromResource for 159 FAILED, error code 2
set up IE plugin keys FAIL