Imported and custom functions not being recognized

All the functions I have written and imported from the File Exchange are suddenly not working anymore.

As an example when I get the following when I run manchester2bin.m which I got from the file exchange. However this function previously worked.

>> manchester2bin('01011010');
??? Undefined function or method 'manchester2bin' for input arguments of type 'char'.

I checked that the folder the function is in is an active path, and also did 'which' and 'exists' to make sure MATLAB sees the function

>> which manchester2bin.m
C:\Matlab\fun\manchester2bin.m  % Has no license available
>> exist('manchester2bin.m')

ans =

       2

All built in functions are working fun (plot, rand, etc...) and the weird thing is if I create a new folder, more that function into it, add it to the path, and try to run the function, it works fine. If I move it back, and do the same process it breaks again. If I simply rename, or copy the entire folder it will not work.

I can't think of anything that has changed recently that would have done this on my computer. I have restarted my computer, and am trying to avoid a re-install of MATLAB because it may take a few days to get that done. I am running MATLAB 2011a on a 64 bit machine.

Any and all ideas would be appreciated. Thank you.

[dpb]

Does seem strange, indeed. I notice the message from which about "no license", though. Never seen that occur that I can recall; not sure what would trigger it for a user-supplied function. Is there some license arrangement associated with it from the FileExchange submission that has gotten lost or corrupted, perhaps?

I'd probably simply completely delete it and reinstall from a fresh copy and see if the symptom disappears before anything else.