In the map module of Lightroom 4.2 RC, I am finding it impossible to navigate around the map using the small map panel on the left.
If I drag the mouse right or down (east and/or south), the map moves itself right and upwards (west and north) and jumps quite large distances. It is better behaved scrolling north. The map very very quickly which makes it hard to be accurate.
In one example I started here in New Zealand and ten seconds later was showing me Mongolia!
Navigation on the map map works as it did in LR4.1 and does not have these problems.
LR 4.2 RC (released 27th/28th August) on Windows 7 64-bit.
Russell