It looks like Alex responded to your emails, but it probably got buried in your spam folder. At any rate, it was mostly a request for info, which you have kindly provided here, so we can ignore that email for now.
I know you mentioned booting with no programs running, but did you go through the whole process of disabling the various startup processes in msconfig? If not, it's worth giving that a shot.
As for DirectX, I'm a little wary about reverting to a previous version of DirectX. If you've been using the web installer up to now, you could try downloading the full redist here: http://www.microsoft.com/downloads/d...displaylang=en
If you've already tried downloading and installing that, you could also try installing the latest SDK,
as that will more likely overwrite the previous data.