[Haskell-beginners] Cabal gives error

[John M. Dlugosz]

When running cabal, it tells me
	Note: there is a new version of cabal-install available.
	To upgrade, run: cabal install cabal-install

And when I do that, it does a bunch of stuff and then

[68 of 70] Compiling Distribution.Simple.Bench ( 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\Distribution\Simple\Bench.hs, 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18
.1.3\dist\setup\Distribution\Simple\Bench.o )
[69 of 70] Compiling Distribution.Simple ( 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\Distribution\Simple.hs, 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\dist\setup\Distribution\Simple.o )
[70 of 70] Compiling Main             ( 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\Setup.hs, 
E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\dist\setup\Main.o )
Linking E:\Temp\Cabal-1.18.1.3-7348\Cabal-1.18.1.3\dist\setup\setup.exe ...
Configuring Cabal-1.18.1.3...
setup.exe: does not exist
Failed to install Cabal-1.18.1.3
cabal: Error: some packages failed to install:
Cabal-1.18.1.3 failed during the configure step. The exception was:
ExitFailure 1
cabal-install-1.18.0.3 depends on Cabal-1.18.1.3 which failed to install.

[C:\Program Files (x86)\Haskell-Platform]

This is, as I recall, where I got stuck trying to get a newer Leksah installed.

Upon finishing, it deletes the temp directory tree, so I can't see if there's anything 
obviously strange with the file it produced.

How do I troubleshoot this?