I know nothing about RawTherapee, and whether or not it has a plugin for
gimp. I know that gimp uses ufraw-gimp to open *.nef files, and I suspect
other 'RAW' formats.
So what I would try would be to move the plugin ufraw-gimp to somewhere
where that gimp will not locate it, such as your home directory, and then
attempt to open your RAW file with gimp. If there is a plugin for
RawTherapee, it should open your RAW file and eventually export it to gimp
when you are done in RawTherapee.
If this turns out to be a cluster-f@ck, and you cannot locate a gimp plugin
for RawTherapee, simply move the hidden ufraw-gimp back to where you found
it.
I'd look for ufraw-gimp with 'locate:' 'locate ufraw-gimp' should be
revealing.
HTH & Good Luck.
John.
--
Using the Cubic at home