Okay I'll try and do it in steps:
1. I'm making a map and used the material view to make a bitmap into into standard texture for it.
2. I exported the textures with wallworm and they worked fine in game (normal creation of materials and exporting is fine).
3. I liked the textures I created and wanted to include them in a different map I was making. As a result of this I added the textures I wanted to carry over, into a material library in the 3dsmax material view.
4. I created my new map and went to my material library in 3dsmax where I was storing the textures I liked and dragged into the material view for the new map
5. At this point I tried exporting the map, but found that the textures I'd used from my library were checkered black and purple in game.
6. Upon investigation I found that the standard materials carried over had "#1" appended to the end of their names, and so had the ingame exported textures.
7. To try and resolve this problem I removed the "#1" from the material names and exported again.
8. At this stage the materials were named correctly and exporting with this correct name, but I was still getting the checkered black and purple error pattern ingame.
9. Next I decided to test to see if the vtf's that were being exported actually opened in photoshop, using the installed plugin.
I found that the exported texture I tested was corrupt (It opened with the message "Could not complete your request because v|ImageLoadProc() failed.") and would not open.
11. I then tested a regular vtf that already existed in the mod and had no issue.
I understand that I could have used the wallworm material library generator to fetch working versions of the textures for other maps if required but I felt simply moving the materials I liked into a library in 3dsmax as I made them, to use elsewhere was more convenient for me.
Obviously this is not the case right now due to this issue but it would nice to have the option, in the future.
If you need any further clarification of the steps please ask.