Putting stuff other than mediavps in the mediavps folder is a huge mistake to start with. You're basically crippling your own install.
Make a folder called Derelict or DerelictSCP (whichever you wish) and then copy all the VP files along with the Derelict.bmp file into it. Then make a new text file called mod.ini and copy everything below into it.
[launcher]
image255x112 = Derelict.bmp;
infotext = Five years have passed since the jump node to the Capella system was collapsed, sealing off a massive wave of Shivan Juggernaughts from pushing further into GTVA space. The supernova and subsequent nebula hang like a growing scar throughout the GTVA as light from that event continues to spread across our worlds. You are to take a new tour of duty with the 212th Silver Scythes squadron in the Tau Sigma cluster, a remote group of systems beyond the Altair Jump Node. These are mining colonies, and while the GTVA presence is small, it is nontheless important.;
website = http://www.hard-light.net/;
forum = http://www.hard-light.net/forums/index.php/topic,38019.0.html;
secondarylist = mediavps;
Personally I don't think that will solve the problem but it's the correct way to install mods and it will save you from other problems later. What I reckon is the actual cause of your problem is that there are two different copies of Derelict SCP floating about and ones of them doesn't have the campaign file in it yet for some reason is still available for download. Since I've not paid much attention to Derelict I can't tell you where to find the proper version but I'm sure someone else does know.
