Ausatco,
If both machines are giving the same ntdll.dll error, there has to be a connection. There is a common program that is trashing your OS.
If you do a fresh install this time, load the absolute minimum on your Desktop computer. See of you can get it to error. If not, then install some more software and see if you can get it to error, etc. Once you think you found the culprit, uninstall the offending program on your Notebook to see if it ends the errors on that computer.
I just want to see if you can find the common problem and see if it solves the issue on the second computer too.
Make sure you get all the latest drivers and patches for all software off the net.
Take Care,
Richard