Ok, I think I am getting confused. So you have a Parent Portal (localhost) and then you have added a child (localhost/dotnetnuke) and one or both are not coming up???
I am not quite sure on this, so rather than give advice on your setup I will simple explain how I have done this (parent/child portals) in the past…
First we need to cover the Parent Child dynamic and some pros and cons and different options that are available for a multiple portal setup…
First you need to ask yourself/answer the following question: Why am I setting up multiple portals?
If the answer is: “I have multiple Website that I need to run” then review DNN Setup Options 2 and 3 below.
If the answer is: “I need to have a Parent Child relationship because I am use a module(s) that allows me to push content etc to the child portal and that is what I need” then review DNN Setup Option 1 below.
Likewise, if your answer is: “I want to have a bunch of cheap sites I can resell” then review DNN Setup Option 1 below.
Finally, if the answer is: “I want to have a bunch or quality sites I can resell” then review DNN Setup Options 2 and 3 below.
Option 1 :: Parent Child Single Install, Single DB
This option is for use in only two scenarios in my opinion, cheap sites for resell through a single host account OR you have a parent child relationship that requires a single DB/Set of tables.
Pros: Easy, Cheap, Quick
Cons: If you have to restore a database you end up rolling all sites back unless you do some serious scripting etc. Can be a major issue if you stomp another sites data…
Step 1: In this option, you would create a Single Website with the DNN Portal in the root as the parent (i.e. localhost). Then for each child portal that is a “/something” you create a virtual directory in the parent portal website with the name (something) and point it back to the same installation location. If you want something.localhost (i.e. support.mysite.com - as I would not recommend actually using something.localhost…) then you can just add this alias to your DNS and then move to the next step.
Step 2: Once you have completed step one, log into the parent portal as Host (or other super user) and go to Host > Portals and configure the new portal using the correct names/paths (i.e. localhost/something OR something.localhost as shown above).
Step 3: Browse your new Child Portal!
Option 2 :: Portal Using Same Database, Different Physical Install Files
This option is ideal if you need to have a single database, but either wants to have more controlled backup and recovery options in the database etc.
Pros: Still easy and gives better database recovery options
Cons: still shared, can still have DB and other issues (not totally isolated)
Step 1: In this option, you would create a first portal (i.e. localhost) and during the install you will specify a unique database object qualifier (unique to each site you want to setup). Then for each additional portal that is a “/something” you create a virtual directory that points to a new folder with a fresh copy of DNN in it. If you want something.localhost (i.e. support.mysite.com - as I would not recommend actually using something.localhost…) then you can just add this alias to your DNS, create a new site that points to a new install of DNN. Then during the install (applies to both options above) you would again select the same database as the first portal and again select a unique database object qualifier (allowing unique table names in the db, but still using the single db).
Step 2: Browse your new Portal!
Option 3 :: Fully Isolated Portals Using Separate Installs and Databases
This option is the one I suggest unless there is a very specific reason why you cannot (noted above).
Pros: Everything is isolated; they are separate in every way
Cons: Obviously this one can cause a little more work (then just a DNS entry and a alias) and requires multiple databases etc
Step 1: Just create a database, setup and folder for the DNN Files, Setup a website in IIS, browse and follow the prompts…
Step 2: Browse the site
I hope the two above mirrors your scenario and give you the info you need.