Hello,
Since my post, I decided to completly re-install the poweradmin and both ccomments and matukio. Initially I still had the error, but after disabling ccomments, it started working. I then re-enabled ccomments module and was expecting it to fail again, but it hasn't?!? So, I'm a little confused!! Anyway, to not waste your time, please ignore this. If it comes back I'll raise a ticket and capture the full message this time.
In answer to your questions as to where I got the error; it was in the module manager - when i click the position button, I normally get (via jsn poweradmin) a pop up showing me graphically where the module could go. After ccomments was installed, this broke, showing me a SQL 1064 error saying there was something wrong with the sql query.
Happy Christmas!
cheers Pete