When I start seeing this problem on my DNN instance, it generally means my log files have gotten a wee bit out of hand and need some manual intervention on my part. 

These are some sites I've found to help successfully control my log-related issues.  Hope some of these help you.

http://www.doyleits.com/Resources/TechnicalBlog/tabid/115/EntryID/3/Default.aspx

http://dnnblog.venexus.com/DNN+And+SQL+Server+Performance+Issue.aspx (very helpful)

http://www.ventrian.com/Support/ProductForums/tabid/118/forumid/3/postid/17467/view/topic/Default.aspx (for "log viewer unavailable" problems)

http://www.mitchelsellers.com/Blogs/tabid/54/ArticleType/ArticleView/ArticleID/69/PageID/37/Default.aspx

Mitchell Sellers site is awesome for DNN help! (http://www.mitchelsellers.com).

eck two wrote Read closely my instructions on how to change the settings.  Where you changed the values only applies to new portals from that point on and does not impact existing portals.

Sorry, you are correct I did not read your post fully.

you say goto Admin/Settings/Advanced Settings/Host Settings

I went to Admin / settings (I assume that's 'site settings') /  'Advanced Settings /

but don't have a section called 'Host Settings' All I see is 'Security Settings, Page Management, Payment Settings, Usability Settings and Other Settings' in the advanced section.

Am I still looking in the wrong section?

Thanks