I don't know if it is the stock behavior of the mod, or something you have done to change it, but the links from the sidebox are malformed - except for top categories, they don't accurately show the cPath, which causes the main column display and the breadcrumbs to be incomplete. Rather than try to fix this and remove the products from the sidebox, you might try another categories sidebox mod if you want expanded categories. Fragfutter's Uncollapsed Categories Tree works smoothly and does what you want. You can get it from his site, linked from his forum thread, or in Categories Dressing.