Installer has insufficient privileges for C:\Program Files, in spite of UAC.
Created originally on Bitbucket by maphew (Matt Wilkie)
I got the following permissions error on Win7 sp1 x64 when installing from tortoisehg-2.9.2-hg-2.7.2-x64.msi. This happens in spite of answering "Yes" to the initial user elevation prompt near the beginning.
Installing worked on the 4rth attempt, after rebooting Windows.
I was upgrading from previous version. My guess is that the folder was in use by the old version and the actual error is along the lines of "folder/files are in locked or in use" instead of "insufficient privileges".