8800 GT drive bug

First post for a year or three. Sorry it's a rather long one but want
to give full background.

My XP (SP3) PC uses an 8800 GT with 512 MB. The driver version I have
been using for several years is 306.3. I've recently started getting a
BSOD when using my video editor to export an MP4.

https://dl.dropboxusercontent.com/u/...-Dec2015-1.jpg

As you see, it points to nv4_disp.dll as the probable culprit.
Presumably something has changed, but I can't fathom what. However, I
have had several hard crashes apart from the BSOD, mainly when using
my video editor (Movie Edit Pro 2014) so maybe that's another possible
cause.

After much research I found this article about the BSOD and followed
its instructions to download a replacement nv4_disp.dll file.

http://www.personalcomputerfixes.com...isp-dll-error/

That seems to have allowed me to succeed with the export on the one
occasion I've tried. But I'm left with some questions which I hope the
experts here can answer please:

1. How can a DLL be replaced by one less than half the size?

2. This screenshot was taken shortly after the successful export, yet
the file has somehow become the original again!
https://dl.dropboxusercontent.com/u/4019461/nv-02.jpg

3. Has this bug (if that's what it is) been fixed in more recent
versions of the driver?

4. Which version is recommended for a user like me, no games but some
intensive video editing/rendering?

5. Why are there so many apparent duplicates of this file, and at
least two sizes?

6. Can I expect another similar export to work, or have I got to
replace the DLL with the small substitute again? (This is typically a
3 hour run, so not keen to repeat lightly without being confident it
won't cause a BSOD again.)

Any advice would be warmly appreciated please.

--
Terry, East Grinstead, UK