If you have several textures in different texture slots of a material, and have set different button display properties for each slot (such as collapsing the mapto tab or other tabs) which are different between textures, then if you try to move a texture using the copy and paste buffer. The material button tabs will go crazy and quite often overwright the their display.

Its difficult to explain and I'm in the middle of BSoD at the moment and its a real pest. I will see if I can get a blendfile for you to test. Although I suspect its quite easy to recreate with a simple multiple texture material.

Cog