It's the patch that comes free with the 2004 disc, not the downloadable patch (there may be a difference between these). I have no problems with High Dive.
(If you want it, Mr K: I'd be glad to mail it or put it online, but be warned that High Dive is definitely not a difficult level.)
In Tanks A Lot, the Water Lems should just fall into the huge tank and live. With me, 50% will not survive that fall, making it impossible. It's also a problem in My Finest Moment.
I'm not sure if it's perhaps a Vista issue, but it seems unlikely it is.
Not sure if the "forcing Lem through floor" is a bug... it's very handy in certain levels and a right pain in the rear for others. And you also have it in regular Lemmings.