I just cannot work out what on earth is going on but after a fresh install when I try and install things like Visual Studio, Adobe Acrobat or MSN Messenger they default to "C:\Windows\Program Files (x86)".

What I don't get is a search in the registry for "Program Files (x86)" comes up blank, so does "C:\Windows\Program Files", as well as "%\Prog" (incase it's using a short name). The ProgramFiles and ProgramFiles(x86) set variables are both correct (pointing to D:\Prog...) and the registry values at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion are both correct.

Of course other installation programs work fine and detect the correct folder but a lot are not and I am totally stumped where they're getting this Windows\Program Files (x86) directory from.

Anyone got any idea's at all what could be causing this?

look at the registry entries here
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion

this r the standard entries on a clean x64 installation
CommonFilesDir, C:\Program Files(x86)\Common Files
CommonFilesDir (x86), C:\Program Files(x86)\Common Files
ProgramFilesDir, C:\Program Files(x86)
ProgramFilesDir (x86), C:\Program Files(x86)

maybe something have changed here o_O

Well I think that fixed it. For some reason the keys there were
CommonFilesDir(x86) and ProgramFilesDir(x86)...see the tiny difference? Added 2 more keys with spaces in and so far all installations seem to be using the right directories.

So thanks for that, one of those things I would've never ever noticed, a missing space!...The question is, how on earth did it happen on a fresh install? o.o