When implementing a workroom in EPiServer 4.51 I found this rather nasty "feature":
In the following code-behind files:
/templates/Workroom/Templates/UnitsNews.ascx.cs
/templates/Workroom/Templates/BulletinBoard.ascx.cs
The following line of code can be found:
PageType pageType = PageType.Load("Ordinary web page");
Guess what happens if you decide to give your page type a different name? I solved the issue by using the PageTypeID instead...
The problem with PageTypeID is that this is defined when the page type is created. If you know what id you have it's ok but it will not work if you export and import your page types to another episerver site.