My problem is that I cannot get a simple WatiN test to reliably work on my development machine which is running Windows Server 2008 and IE8.
I have seen a couple of
IE8 definatley works with WatiN, and has done since the first public release of IE8.
If something is working in debug but not when running it usually points to a timing or Server 2008 security lockdown issue.
You should putting the line that is failing in a try catch, then if there is an exception pause for say half a sec and then re-try again.
Also ensure that you have turned off all the extra server security lockdowns, and are running nUnit as administrator to avoid UAC getting in the way.