Peter:
I just purchased and downloaded 4.0.0.1 from Snowcovered and proceeded down the road to an upgrade.
Following the installation instructions the first order of business was to upgrade 4.5.1 to 4.5.5, (why just stop at 4.5.3 was my thinking). After the upgrade, I now find my Host tab is no longer available as superuser. So, I checked on DNN and sure enough this is starting to become an issue for 4.5.3+ upgrades. In my case a show stopper since my site has over a thousand users depending on DMX 3. Have you heard of any possible solutions to this problem, since I cannot install DMX 4 until I have at least DNN 4.5.3 installed and working correctly?
Any insight would be helpful.