I just added a new user to the system (Ubuntu 14.04 LTS server) using

adduser --force-badname myNewUser

After deleting it again with:

deluser --remove-all-files myNewUser

the system was fetching data from the disc (as expected) but it was fetching a long time (not expected) and finally it gives me a huge list of a strange output:

/usr/sbin/deluser: Cannot handle special file /proc/22220/fd/0

/usr/sbin/deluser: Cannot handle special file /proc/22220/fd/1

/usr/sbin/deluser: Cannot handle special file /proc/22220/fd/2

and so on.

After reading this answer I now know that the proc-directory is just a directory living in the memory. This just tells me that the files will be gone when rebooting my system. However it does not solve my issue.

Searching on google just shows up bug reports or a thread which states that deluser --remove-all-files is an old way deleting a user?

What does this output mean? Is my system now messed up? If so, how can I bring my system back on the right path.