Similar problems were encountered here with 5.2.3 - I gave up on that because I had successfully installed 5.2.2 a couple of times.

5.2.2 When installing on the local SQL Server 2008 and don't configure the db in the web.config file you need to note that the dbowner checkbox is ticked but greyed out on the Integrated Login option. I had to select the the non-integrated option and enter a user name/password of a user with dbo rights to overcome this issue.

You also need to manually give the 'Network Service' login access to the DNN database. Integrated mode might work if you give the 'Network Service' the sysadmin role permission but I doubt whether that's a good idea or not.

A pet peeve of mine - and I'll express ir here - is the presumption of the so-called experts that us mere mortals are stupid and can't follow directions. This is a case where a simple 'ticking the box you fool' was not very helpfull no matter how well meaning it was intended.