To those who are still having problems with LR4, I would only say again, that the solutions I found are still working - LR4 lon my computer does NOT have the problems that some of you are so irate about. So what did I do? I upgraded my catalog from LR3 to LR4 and had all sorts of strange problems, so I deleted my previews folder (all the previews plus the previews.db and rootpixels.db - this is on Windows. Macs have a different folder/file for previews). I also cleared the acr cache to that was empty. Then I went in to Library/previews and with All Photographs selected at the top of the LH panel, I told it to Build All Standard previews. When that was done I told it to Build All 1:1 previews. Building all those previews also populates the acr cache with new xxx.dat files. That solved most of the problems, and it has worked for others on this list. But there were still one or two strange things happening, so I repeated this again after Exporting my upgraded catalog to a new catalog (without previews). That clears out any rubbish left over from the LR3 catalog that might be upsetting LR4. After creating all the new previews again with the new exported catalog, and recreating the acr cache again, everything was fine, no problems at all. So please try it. If it doesn't work for you, then let me know, but don't keep on complaining if you haven't tried it. To complete the clearout of old stuff, you might also trash your prefs file. Make sure you trash any old LR3 prefes files as well, since LR4 may try and use your old prefs file if it can't find your current one. So make it produce a completely new one and reset your prefs in the new one. Why is this necessary, some may ask? Well, as I said above, some LR3 stuff left over in the catalog can upset LR4. And if you have had any crashes with LR, the previews, previews database, andr cache can get corrupted and be out of sync with the catalog, thus slowing down the whole process of getting the right previews when scrolling through them. So, 1 Trash your prefs 2 Clear your acr cache. Make sure it is big enough to hold 1:1 data files for all your raw files. 50K of raw images needs about 30GB of ACR cache. 3 Export your upgraded catalog to a new one. 4 Delete your previews folder and create all new standard and 1:1 previews. 5 Use the latest version of LR4 - 4.1RC2 or 4.1 when released (soon I expect). Bob Frost
... View more