hi folks,
i guess most of us know when GECK start up each time,
it will run some register code checking like file types, etc.
and will override any "Wrong" register code it founds. which is prettry normal.

the only problem is,
the New Vegas GECK will set HKEY_CLASSES_ROOT\.nif default as "BGS.ArtFile",
which will direct to HKEY_CLASSES_ROOT\BGS.ArtFile
it's alright since you can still add other progran like NifSkope into window's Open with list,
and make window open .nif with NifSkope,
but for some other program like Winrar,
no matter what you did, it will try to open .nif with the GECK,
and the GECK will sya you're having a Invalid directory,
may be because GECK can't read the TEMP folder.

this never had happen with Oblivion or FO3 kit,
luckly 7zip don't have this issus, it doesn't annoy me much,
just asking if Bethesda are going to fix it or they are just going to leave it

If I understand that correctly, and I am in no way sure that I can decipher that mess, you're trying to open a .nif that's compressed inside a .rar file with Nifskope instead of the GECK?

Try opening a .nif in a .rar file that has no compression, since perhaps that is the problem. Failing that, disassociate the GECK with .nifs and have nifskope (or whatever) be the primary program instead.

If 7zip works then stick with it though, it's a far superior program, and GECK updates are usually few and far between.

Well, it's not really Bethesdas problem what Winrar does. If I remember, Winrar has options somewhere for what to use for opening certain file types other than the default window settings. (I use 7zip these days, so I can't really check for you)

does this for me when i installed F3.

The problem here is not with WinRAR but with GECK. It rewrites its Windows Registry settings every time it's started.
I'll probably fix it in PowerUp sometime, unless it can be changed in the INI (I can't find any corresponding options but maybe they exist).