Exception: Unable to create type ‘XXXXXXXXXXX.MenuAdapter’

[Exception: Unable to create type ‘XXXXXXXXXXX.MenuAdapter’.]   System.Web.Configuration.HttpCapabilitiesBase.GetAdapter(Control control) +2625202   System.Web.UI.Control.ResolveAdapter() +117
System.Web.UI.Control.InitRecursive(Control namingContainer) +30
System.Web.UI.Control.InitRecursive(Control namingContainer) +279  System.Web.UI.Control.InitRecursive(Control namingContainer) +279   System.Web.UI.Control.InitRecursive(Control namingContainer) +279   System.Web.UI.Control.InitRecursive(Control namingContainer) +279   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean

We started to get this error after we applied SP2 on MOSS, while we had this error previously we were not able to reproduce it all the time.  After we applied SP2 it happened consistently and it turned out that the .browser file for our custom menu did not contain the fully qualified reference for the assembly.

.browser Before

<browsers>
  <browser refID="Default">
    <controlAdapters>
      <adapter controlType="MOSSCustomization.MossMenu"
               adapterType="MOSSCustomization.MenuAdapter" />
      <adapter controlType="MOSSCustomization.MossMenuLeft"
               adapterType="MOSSCustomization.MenuAdapterLeft" />
</controlAdapters>
  </browser>

.browser After

<browsers>
  <browser refID="Default">
    <controlAdapters>
      <adapter controlType="MOSSCustomization.MossMenu,MOSSCustomization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=XXXXXXXXXXXXXXXXXXXXX"
               adapterType="MOSSCustomization.MenuAdapter,MOSSCustomization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=XXXXXXXXXXXXXXXXXXXXX" />
      <adapter controlType="MOSSCustomization.MossMenuLeft,MOSSCustomization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=XXXXXXXXXXXXXXXXXXXXX"
               adapterType="MOSSCustomization.MenuAdapterLeft,MOSSCustomization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=XXXXXXXXXXXXXXXXXXXXX" />

</controlAdapters>
  </browser>