Continuing from the http://www.gamesas.com/topic/1508231-rel-oblivion-script-extender-obse-0021-2/

OBSE - The Oblivion Script Extender
OBSE is a modder's resource that expands the scripting capabilities of Oblivion.

It doesn't make any modifications to Oblivion.exe, TESConstructionSet.exe, or any other files in your Oblivion install, so don't worry about permanent side effects. As of v0017, OBSE requires the 1.2.0.416 version of Oblivion.

http://obse.silverlock.org/download/obse_0021.zip - current stable version, recommended for general use
http://obse.silverlock.org/
http://obse.silverlock.org/obse_command_doc.html - link is for v20 documentation. v21 documentation is included in the download.

What's new:

Readme (abbreviated):

For mod developers:
http://oblivion.nexusmods.com/mods/36370 - An OBSE plugin that fixes bugs in the CS and adds new features to it

So here's something funky. I just tried recompiling my OBSE .dll, and visual studio C++ express gave me the same XPath errors.

WTF?

Maybe this can help with the problem: http://www.bultreebank.org/clark/errorsOnline/data/XPath-Error-Messages.htm

Googling "visual studio c++ express xpath error" brings up some potentially helpful links.

I figured it out. I recently installed a bunch of MSI utilities so that I could check on what my clock settings were. It occurred to me that often times these sorts of things are just fluff / bloat ware.

I went through all my programs and uninstalled anything that wasn't necessary and the errors went away. Crossing fingers this will also resolve my stack hash CTD issues as well.