In trying to install the new versions of Refactor! for VB and ASP.NET, I came across this annoying problem.

I was getting a very unhelpful "internal error 2739".

It turns out that this is the MSI error code for "Could not access JavaScript runtime for custom action" (you get to see that more helpful message if you turn on MSI logging).

The first link above suggests re-registering JScript.dll.

I tried that to no avail.

But I'm running Vista x64, so I wondered if there were different versions of regsvr32.exe? A quick search of my \WINDOWS folder confirmed there are - in the \WINDOWS\SysWOW64 folder there's another version, and guess what - there's also a different version of jscript.dll!

So, I tried the following, then re-ran the installer for DXCore and Refactor, and success :-)

cd c:\Windows\SysWow64

regsvr32 jscript.dll