From the log you provided, it seems Microsoft_VC80_CRT_x86 payload installation failed, you can try to do the following steps:
1) Go to payloads\Microsoft_VC80_CRT_x86 directory in the AD 2.1 installer path.
2) Double click Microsoft_VC80_CRT_x86.msi to install it manullay, you can choose to remove it first from the prompt dialog, then install it, or repare it to make sure Microsoft_VC80_CRT_x86 is installed successfully.
3) Relaunch AD 2.1 set-up exe.
You can refer to the thread : http://forums.adobe.com/thread/664080?decorator=print&displayFullThread=true
Any further problems, pls post here, thanks.
Yes. That solved the problem.
I first ran repair on VC80_x86 as suggested, and then re-ran the installer. It failed again, but it did get past the VC80_x86 payload, and instead died on VC90_x86. In the end, I had to manually run a repair on all three of the Microsoft payloads before the installer made it through okay.