Everytime I load unity scripts missing

[amigax]

There is something very odd about this package but I cannot work out what. Whenever I reload unity NavMesgSurface etc are missing from all my objects. It is highly frustrating, what is it about this that is doing that?

[amigax]

hmm not sure why but I think I fixed it by copying the code to a text editor, deleting file then copying it back. Never seen this happen ever in unity.