Creating a Portal site in WP - any thoughts?

[j0s3]

Hi all,

I'd like to create a site where users get to log into their own private area,
post questions (privatly) and have them answered by admin (again, privately).

I'm contemplating how to do this...

I thought of installing WP, then creating subdirectories (1 for each member) and
installing 1 WP in each directory. In effect this gives them their own blog, through
which they get to interact with admin.

OK that just LOOKS like the wrong way to do this. Potentially, with 100 members,
there would be 100 blogs installed in subdirectories... it's a nightmare.

So I'm looking for a solution where the member logs into 1 WP bog, and gets their own
private 'bit'. They won't see other members' posts etc... only their own posts, and the
answers to those posts (by admin).

In effect this would be a ticket/support system, so any advice on plugins is also welcome.

If anybody can advice or point me in the right direction, I would be very grateful.
Preferably I'd like a solution I can use with WP.

Many thanks
Jose