substrings of text like '18-Oct' or 'PDCLOLPT00' are getting converted to the associated smiles.
That behaviour has been changed recently. Try a devel snapshot, it might be working as expected now.
Is there anyway of configuring dokuwiki to not use smileys? Must I delete the smileys.conf?
AFAIK smileys.conf must not be deleted! Try emptying it instead. (Not tested! Make a backup in case it will break something.)