I have been trying to install YAF for hours. I gave up on trying to install it on the same server as the current website. I am now trying to install it on a web server without a website on it. When I try to run install/default.aspx I receive this error: The type or namespace name 'ProfileCommon' could not be found (are you missing a using directive or an assembly reference?)

I followed the instruction and unzipped the download, then ftp'd the entire folder to the web server. The server is Windows hosting with .net 2.0.

Candyce, I just a simple question. You copied the recommend-web.config file to the root and renamed it web.config correct?

Yes.

Did you create the forum in a virtual dir?

I tried to follow the instructions in the installation section of the wiki as follows:

http://sourceforge.net/project/showfiles.php?group_id=90539 
Unzip all the files and upload the entire directory structure to a directory on your web server.

I unzipped it to a folder on my local hard drive first, then used ftp to upload everything in the folder to the web server.

2. Download and install SQL Server. Create an empty SQL Server 2000/2005/Express database for YAF and add a user with valid permissions to the database. (Information to be used in the next step.) There are many ways to create a SQL database. It really depends on the tools at your disposal and the version of SQL Server you plan to use.

A SQL Server 2005 database already exists on the web server, so I didn't do anything.

3.Modify the Web.config file (on the server) you just unzipped. If Web.Config is not present you can copy default.config and rename to web.config, then modify.

I copied dev-recommmended-web config and renamed it. FTP'd it to the web server.

http://www.connectionstrings.com/ . The database pointed to by can be an already existing database, or you can create a new database to install to. Hint: If upgrading, use your current web.config values in the new web.config.

connstr doesn't exist in the web.config file. I updated the database connection string in db.config

If YetAnotherForumNET isn't installed at the root directory of your web server or host, make sure the files in the bin directory of the zip file is copied to /bin on your web server. Also you'll need to add the element to the web.config to point to the correct URL. Example: If you have install the forum in the directory "http://www.yoursite.com/forum/yaf/" you will need to add /forum/yaf/ to web.config. Please refer to these URLs if you still have questions about the application root:
http://www.iisworks.com/faq/kb.asp?a=show&ID=164 
http://forum.yetanotherforum.net/Default.aspx?g=posts&t=2942 

It is installed in the root directory.

5. Open the file /install/default.aspx on your web site. If you are testing on your local computer, under a directory called "YetAnotherForumNET", the address should be: http://localhost/YetAnotherForumNET/install/
Follow the directions provided in the wizard.

This is when I receive the error message.

I've encountered this problem too... it's usually a misconfigured asp.net installation/web. Verify that your host is running on the proper version of asp.net. Try the different releases of YAF... NET v2 and v3.5 if that doesn't work.