This error was reported here:

http://lists.wfu.edu/pipermail/gretl-users/2014-May/010061.html

but it was an off topic.

Ah that's funny, I see it was me myself and I who reported that problem. Did you see (later in that thread) Allin's speculation that the gretl install was corrupted and that I replied "An explicit uninstall-reinstall indeed eliminated those problems on the Win-8-machine"?

So that would be my recommendation: Cleanly uninstall any previous gretl version before re-installing. (It's pretty quick.)

Regarding "D:" and "C:", I have two disk partitions (C: and D:), where gretl is installed in C: and the directory where I work is in D:.

OK, I thought so.

good luck,

sven