[wcopel]

When importing images in LR4 I have very good exposures in the preview window but in the main window while loading its good but when loading is complete the images sometimes becomes overexpose and on occasions underexpose. I have windows 7 OS 8 gigs of memory please help.

[wowzer]

How do they look in Photoshop or another editor?

Not uncommon for preview/thumbnails to look good.

What does the histogram say?

[colinsp]

If you shoot in RAW the initial images that are pulled in are the jpg thumbnails within the RAW file. This jpg's are processed by you camera when they are created and so look different to the RAW image which is unprocessed. Once the RAW's are in then LR creates its own thumbnails from the RAW's in its catalog file. These thumbnails update as you process them.

[wcopel]

Thanks