Can I check what data you are trying to restore.
Also you downloaded BE 15 from the site, but at what level, as there are 4 different installation packages there, but Feature Pack 5 was the last major release ? There were 5 Hotfixes released after that, that would ideally need to be applied on top of FP5 if that is the version being used? It depends whether you have any Lotus Notes data that needs to be protected, as Notes support was removed during the BE 15 release.
If little has been done so far, it may be better to uninstall BE 15 completely and rename any remaiing Catalogs folder. I would then recommend downloadng and retrying with theand then apply the Hotfixes (under Updates), to see if this is seen better. I found a similar 'InsertAdhocSolution' error in an old case, that appears was resolved by upgrading to the FP5 release.