Using WebParts results in blank page

Question

I'm developing an ASP.NET (C#) application using EPiServer CMS 5. On the startpage we have four WebPart-zones and everything works great running it through Visual Studio. When publishing it to the production-server (IIS 7) the startpage shows as a blank page, no error what so ever...

When we remove these lines of code it works, so it has something to do with the WebParts.

<WebParts:ExtendedWebPartManager ID="WebPartsManager" runat="server"></WebParts:ExtendedWebPartManager>
        <WebParts:ExtendedWebPartZone WebPartProperty="WebPartZone1" runat="server" ID="WebPartZone1" PartChromeType="None" AllowLayoutChange="false" Padding="0" PartChromePadding="0" Width="100%"></WebParts:ExtendedWebPartZone>
        <WebParts:ExtendedWebPartZone WebPartProperty="WebPartZone2" runat="server" ID="WebPartZone2" PartChromeType="None" AllowLayoutChange="false" Padding="0" PartChromePadding="0" Width="100%"></WebParts:ExtendedWebPartZone>
        <WebParts:ExtendedWebPartZone WebPartProperty="WebPartZone3" runat="server" ID="WebPartZone3" PartChromeType="None" AllowLayoutChange="false" Padding="0" PartChromePadding="0" Width="100%"></WebParts:ExtendedWebPartZone>
        <WebParts:ExtendedWebPartZone WebPartProperty="WebPartZone4" runat="server" ID="WebPartZone4" PartChromeType="None" AllowLayoutChange="false" Padding="0" PartChromePadding="0" Width="100%"></WebParts:ExtendedWebPartZone>

Answer 1

Resolved by "re-installing" the webpart framework for EPiServer...