Our workaround was to update the registry manually (obligatory warning about doing this on your machine!)In addition to this check if there is association for .jnlp in the HKCU branch. If you ever tried "Open with" then windows will add association to user branch and it will hide system wide settings.
Then edit that value to point to a 32-bit javaws.exe – this one happens to be in the jre7 folder:
"C:\Program Files (x86)\Java\jre7\bin\javaws.exe" "%1"