I had a similar issue; the installation process would hang for a long time while my AV (Kaspersky) decided to hog the CPU, then the two error messaegs described would pop up.
On viewing the quarantine area for the AV, there was c:\Program Files\Splunk\Bin\Python.exe.
I attempted the install again, pausing the AV beforehand, and it worked a treat.
This isn't specific to 32- or 64-bit machines, but it's another option to look at for anyone having this problem.
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