[Lejo]

You might, for example try editing your load.ini. Take this part:

[WOOD]
Wood0 = forest/summer/skwood0.tga
Wood1 = forest/summer/skwood1.tga
Wood2 = forest/summer/skwood2.tga
Wood3 = forest/summer/skwood3.tga
Wood4 = forest/summer/skwood4.tga

and change it into

[WOOD]
Wood0 = forest/summer/dlv_skwood0.tga
Wood1 = forest/summer/dlv_skwood1.tga
Wood2 = forest/summer/dlv_skwood2.tga
Wood3 = forest/summer/dlv_skwood3.tga
Wood4 = forest/summer/dlv_skwood4.tga

or for that matter change it into ANY set of forest textures which are in your ..._Tex/forest/summer folder ...

I haven't downloaded this map so can't check it but maybe this forest error occurs because there is a mistake in your load.ini with the stock Slovakia trees?
Instead of Wood0 = forest/summer/skwood 0.tga shouldn't it be Wood0 = forest/summer/sk_Wood0 .tga