I have the following situation: I have a material with a texture which I load from file.In some cases I just load the image, create OpenGL texture and generate mipmaps.Then just render it.Works fine when minimized.In other cases,I do some processing on that texture after the initial mipmaps generation.And because I do the processing only on the level zero I regenerate the mipmaps before returning to the renderer.The issue is that after second generation of mipmaps they don't exist.The texture looks as if it has GL_NEAREST mag and min.I can't understand why it doesn't work second time.Here is my code to generate mipmaps:

glBindTexture(GL_TEXTURE_2D,_id);
glTexParameteri ( _target, GL_TEXTURE_BASE_LEVEL, 0 );
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D,0);


My hardware is NVidia QUADRO K4000 ,OpenGL 4.2
One more thing.In OpenGL debug output I am getting the following warning:
State usage warning: Texture 2 is base level inconsistent.Check texture size.Severity:low ,ID131204