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Running `python setup.py bdist_wininst --user-access-control=force` produces invalid installer that fails to install with the error message:
Failed to start elevated process (ShellExecute returned 5)

See also issue8871 and original report http://scons.tigris.org/issues/show_bug.cgi?id=2533 

Is it possible the installer is being run from a network share? A comment from PC/bdist_wininst/install.c:
	// interesting failure scenario that has been seen: initial executable
	// runs from a network drive - but once elevated, that network share
	// isn't seen, and ShellExecute fails with SE_ERR_ACCESSDENIED.
SE_ERR_ACCESSDENIED is 5, so googling for that might offer more insights.

It is local Ext2 partition system accessible through http://www.fs-driver.org/ on the same HDD as primary system partition. But there is definitely issue with difference between drives.
There is no problem if the package is executed from the NTFS system drive - permissions asked as expected, no errors. On the Ext2 partition VLC and other installers that require elevated privileges fail. I do not remember any such problems last year, but it just can be that most applications on this drive are not windows specific or do not require elevated privileges.
I still doesn't explain why this drive is threatened as "network". It would be nice to see how Windows treats other partition types - FAT32 or FAT16.

Attaching installer file for testing.

This is listed as a known limitation of the Ext2 FS driver. From http://www.fs-driver.org/relnotes.html :
===
Running programs on an Ext2/Ext3 volume on Windows Vista 
Currently it is not possible to start a program on Vista if UAC is enabled and the program's executable is stored on an Ex2/Ext3 volume. An "invalid parameter" message box appears, but the program does not start. 
UAC is the feature of Vista that prompts the user to elevate the user privileges to administrator level when necessary. UAC is enabled by default. It is not recommended to disable it. 
The problem is caused by Vista's internals: There is some code that compares whether the name of the file system type is one of the following: "NTFS", "FAT", "FAT32", "CDFS", "NPFS", "MSFS" or "UDF". If there is a match, it is one of Microsoft's file system types and a lot of code is skipped in the Multiple UNC Provider (MUP) implementation of Vista. If the file system type is a third-party type, for example "Ext2", some code runs in the MUP of Vista that always generates an ERROR_INVALID_PARAMETER error status code due to a bug of Vista.
===
So the bug is in that FS (or in Windows if you will). It is not something Python can fix.

Thanks for thorough explanation. Can somebody close it with some resolution like "Can't fix. OS level problem"?

Is it possible to detect this situation and display more user-friendly error message with a reference to this issue?

Please add issue8908 as superseder.