mine went wacko too ... I had to do a force reset to factory default and deleted all the "saved settings" I'd made.
check if its doing auto-exposure on anything in your preferences. If you then do a manual contrast setting it seems to do it again on scan essentially doubling things.
I highly recommend scanning neg as pos in my workflow
http://cjeastwd.blogspot.com/2009/10/quick-negative-scan-tutorial.html
PS ... a scan from yesterday in full sunlight in snow
done using my above method. Using scan as neg my LS-4000 blew out the snow and gave way more grain in the shadow blue/cyan areas
I happened to be comparing my G1 (with a 1/2 focal length lens) and noticed that I got this level of detail
and that top LS4K image was scaled back from 3657 pixels high to 3000 pixels high to make the comparison with the G1 easier.
gosh I like negative for capture