Why did I get errors in my App_Web_olwtcupi.4.cs page?

I have an error I haven't seen before. One minuter the debugging works fine, the next a App_Web_olwtcupi.4.cs opens in Visual Web Developer (2008) with the following code marked:

[System.Diagnostics.DebuggerNonUserCodeAttribute()] public motesforslag_aspx() { //'motesforslag_aspx': Expected class, delegate, inteface, enum or struct string[] dependencies; //'] dependencies': Expected class, delegate, inteface, enum or struct #line 912304 "C:\Users\karask\Documents\Visual Studio 2008\WebSites\WebSite1\MotesForslag.aspx.cs" ((global::System.Web.UI.Page)(this)).AppRelativeVirtualPath = "~/MotesForslag.aspx"; #line default #line hidden if ((global::ASP.motesforslag_aspx.@__initialized == false)) { dependencies = new string[4]; //'string': Expected class, ...