It appears the plugin added a column 'visibility' to the categories table... The SQL is joining categories and albums - and each now contain a 'visibility' column - so MySQL doesn't know which is intended...
The SQL defines the category table as 'c', and the albums table as 'r'... You didn't say what release - but in 1.5.44, this code exists at line 322:
// collect album info and album counts
$sql = "SELECT aid, title, r.description, keyword, alb_hits, category, visibility, r.thumb, r.owner, depth AS level, lft, '0' AS pic_count
FROM {$CONFIG['TABLE_CATEGORIES']} AS c
INNER JOIN {$CONFIG['TABLE_ALBUMS']} AS r ON r.category = c.cid
WHERE c.depth >= $CURRENT_CAT_DEPTH + 1
$forbidden_set
$lft_rgt
ORDER BY $sort_order";
Since this is unmodified CPG - and the only albums has a visibility column as shipped - the albums table appears to be what is requested here...
Changing:
$sql = "SELECT aid, title, r.description, keyword, alb_hits, category, visibility, r.thumb, r.owner, depth AS level, lft, '0' AS pic_count
To: (adding 'r.' to 'visibility;)
$sql = "SELECT aid, title, r.description, keyword, alb_hits, category, r.visibility, r.thumb, r.owner, depth AS level, lft, '0' AS pic_count
will tell MySQL which table is requested.
If you don't intend to use the plugin, you could rename or drop the column 'visibility' in the category table instead.
I'd have to take a closer look at the plugin to see what it is trying to do... but one of the above should get you running again.
**Edited to correct sample as pointed out by Es in next post..