It looks like after doing multiple install and uninstall; I found non of JRE bundles are getting installed on the machine. After reboot; I could not reproduce this issue. I could reproduce this issue on XP and Vista (32 and 64 bit) both.
I am atatching snap shot of the error and install log both.

Please include the following information: (Chris G asked to put this infos in the bug)
On Vista x64, once out of how many Vista x64 installs?
This issue occurs suddenly; no fix pattern. But once this issue appears; there is no other way; other then rebooting the machine.

About how many times did you have to reboot the XP machine to get rid of the error?
Only once.After rebooting the machine it is not reproducible.

Was the Error 1606 always when going from 6u10 b32 to 6u11 b00, or other installs also?
No fixed pattern; but reproduce while doing PIP testing for T2 bundles.