So, I've been trying to get a SCM SPR532 working yesterday, but that didn't really want to play nice. Today, I wanted to use my trusty old SCM SCR335 again, but GnuPG kept giving me sharing violations like so:
$ gpg -d secretdocument.gpg
gpg: detected reader `SCM SCR 335 00 00'
gpg: pcsc_connect failed: sharing violation (0x8010000b)
gpg: kaartlezer is niet beschikbaar
(The last line read "card reader not available" in Dutch.)
Very annoying. I tried shooting down the running pcscd, but that didn't help. Then, I uninstalled OpenSC, which seemed to have helped. No idea why, but honestly, the documentation is so very vague, I hardly know how all these components work together.
Anyway, I hope it helps someone.