This symptom arises suddenly one day when the BuiltIt batch script always aborted abnormally while the "Please wait while Windows configures..." screen hangs indicating endless waiting.
Take a look at the event viewer, the source being MsiInstaller and the error reads:
"Detection of product '{E05F0409-0E9A-48A1-AC04-E35E3033604A}', feature 'Visual_Studio_.NET_Ent_Architect', component '{C92518C0-1D92-11D2-AA97-00A0C90F57B0}' failed. The resource 'HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved\{BDEADF00-C265-11d0-BCED-00A0C90AB50F}' does not exist."
The solution was found to be as follows after clueless goggling:
(1) Rename C:\Program Files\Common Files\Microsoft Shared\Office11\mso.dll to mso.dll.bak. Suit the correct office version.
(2) Run Visual Studio or Office, the MSI installer window pops up, let it go and replace mso.dll with a fresh one.
(3) The batch script now activates devenv.exe without difficulties.