Using the latest version of the darcs stable branch.

I have a remote repository hosted on a SunOS machine. I work locally and
push my changes there.

Usually, it works smoothly, but yesterday I got this error after
confirming the patches to push:

"darcs: takeLock my_remote_repos/_darcs/lock in my_repos: atomic_create
my_remote_repos/_darcs/lock in my_repos: unsupported operation (Function
not implemented)"

I tried connecting to the remote machine and running "check" and
"repair" locally. No errors were found.

Today I tried again and it worked. Not sure what was wrong. I am not
able to reproduce the problem again, after copying the repositories
around and trying to push again.

Salty-horse,

Thanks for the report. However, since you can't reproduce the issue and it
doesn't sound familiar, there's not much we can do about it. While a status of
"presumed-dead" might be more appropriate, I'm marking this issue as "wont-fix"
for now.  However, if the issue does come back from the dead, please, re-open
this ticket. 

  Mark