I'm new to Perforce, and it is not going well at all. But currently, I am completely stuck, as all I can get it to say is:

$ p4 open a_code_file.cpp
Locked client 'my_hostname' can only be used by owner 'perforce'.

I have absolutely no idea what I did to upset it, and the error message itself is meaningless gibberish to me. "perforce" doesn't own anything - all the files are owned by me. I am in a Perforce repository, ie, there's a .p4rc a few directories up.

Edit: It only seems to be some files. If I:

$ cd some_other_directory_in_the_repo
$ p4 open a_file

... it works. So it's only some things...