Just had this error for the second time. This occurred when clicking 'Full scan with cleanup'. When this happened the first time, I just re-logged back into Madsonic to correct the issue but now it is persistent.
However, BIG problem. I tried to post the relevant error message as instructed but got this - "Your post looks too spamy for a new user, please remove off-site URLs. "
There are no offsite urls as far as I can see, only general paths to files on the server. Being a new user should not restrict me from posting this kind of output and if I removed all the paths, then my error submission would be meaningless. I don't see what the problem is whether I am a new user or not and I think this is a bit too restrictive for an anti-spam measure as it appears not to work correctly anyway. Oh, by the way, "spamy" should be "spammy"
When I tried to find a solution for this "spammy" message problem, I got
SQL ERROR [ mysqli ]
The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay 
An SQL error occurred while fetching this page. Please contact the Board Administrator if this problem persists.
I really don't see what I can do to report this.....