am having the same problems that you have posted here. However placing the db2jdbc.dll in the domino directory does not help me (i get a driver unknown error). I feel like i have tried everything (i even tried building a new server). Any help you could provide would be greatly appreciated!
here is another post of mine on the same topic
http://www-10.lotus.com/ldd/nd6forum.nsf/ShowMyTopicsAllFlatweb/88b086ba1140a1bc85256d0a00533841?OpenDocument