try this:
right click on the offending .resx file in Visual Studio and select 'View Code'.
replace the base64 resource entry type definition with base32.
here's an example:
<data name="axMapControl1.OcxState" mimetype="application/x-microsoft.net.object.binary.base64">
change to:
<data name="axMapControl1.OcxState" mimetype="application/x-microsoft.net.object.binary.base32">
recompile.