Can you please show a screenshot of your workplace, trying to explain again what you are expecting to see and don't see? I'm not sure I understand what you are saying your problem is.

Beat

Can you see the image when you switch to Develop?

This behaviour is usually caused by one of two things:

• Corrupt Preview Cache. Try the following:
  • Rename the folder "[catalogname] Previews.lrdata" when LR is closed
  • Restart LR, it will build a new previews folder
    
  • see if the thumbs are shown
  • If yes, choose "Render Standard-Sized Previews" from the Library -> Previews menu, and then delete the renamed .lrdata folder
  • If no, shut down LR, delete the newly created "[catalogname] Previews.lrdata" folder and rename the renamed folder back to its original name
    
• Corrupt Monitor Profile. Re-calibrate/re-profile your monitor. If you did not calibrate your monitor with a calibration device yourself, we would need an indication of your operating system to give further advice.

Beat

I have the same problem with previews not showing....they are all gray, just as in the example in this thread. I have the latest version of LR, 3.4.1, running on Vista with all of its updates.  Note that while I say I have the "same problem," my circumstances seem a little different. When I just tried to load LR and this problem existed, I had that same folder up and running with previews no problem this morning.  I had not moved anything around.

This does not happen too often, but I've noticed it more and more in the past few weeks.  The thing is, when it happens, I can exit LR, and the problem will not exist the next time I load LR.

It looks like potential solutions given are to rebuild the preview file(s) or to reload monitor drivers?

1. If in fact the preview files are corrupt, does it make sense that the problem does not happen all too often and in fact does not happen after you exit and then reload LR?

2.  If I rebuild the preview files, should I expect this to take a long time with 31,000+ images in my catalog?

3.  Any other suggestions?

Thanks

You know, when I first installed Windows 7 was playing around with the "Library" and I began placing folders that I thought were relevant to me in it.  One of the folders I placed in the "Library" was the system ICC profile folder and when I added it I also changed the name their to something more relevant thinking that the The Windows 7 Library was kind of like a set of links/shortcuts and it would not affect the name of the actual folder.  Well, obviously, I was wrong and I got the same results you are getting in Lightroom now (Gray boxes).  I changed the name back to the correct one and every thing was fine.  It may not be your problem but thought I would give it a shot.

P.S. Just in case, the correct name and location of the Windows 7 ICC profile folder is;

C:\Windows\System32\spool\drivers\color

I would give the re-rendering of the previews a try.

Beat

I wanted to give an update on this issue, along with some comments and questions.

1.  I have not completed the rebuilding of the Preview files. 

2.  When I did rename the Preview files, as a first step, I ran into a number of problems this weekend.  These problems are certainly related to the way I have my system set up, not due to Lightroom.  But, in case anyone has a similar setup to mine, here is what happened.  I store all of my photos on an internal terabyte drive.  The photos, along with the Lightroom catalogs and previews, are backed up onto an external Western Digital terabyte drive, automatically.  So, any time I make the slightest change in the Develop module, that change not only updates the local drive; it also is backed up (duplicated) on the backup drive.

3.  Because I changed the name of the Preview file, what happened was that yes, the Preview file's name got changed; however, the system then attempted to delete the old backup Preview file while at the same time tried to backup the newly created Preview file.  In short, things got pretty messed up.  I think I have cleaned it up, now....and, again, I believe this is probably a problem due to the backup system I have, possibly not being able to handle the deletion of a 10 Gb preview file and creating a new one!

4.  Anyway, my question is about those preview files.  I was always under the impression that any time you load an image into LR, an image preview is created for that file.  Is that correct?  Or, do you have to go through that build process, Library - Previews - Render?  I never have done this before, yet there has always been a Preview file/folder.  I have seen cases before, when I load a set of photos into LR, it appears as if Previews are not created unless I scroll down through the picture and actually highlight some of them.  Does this scrolling through the pictures have the same effect as rebuilding a preview (Library - Previews - Render?)

Further, I also have multiple Folders in my Library.  It appears as if when I go through this rebuild process, it only rebuilds those images on whose main Folder I have highlighted.  While I have 31,000+ pictures in my entire Library, if I only highlight the folder "Pictures from Others," which has only 681 of those images, it appears as if only those 681 are rebuilding previews.  Is this a correct understanding of how rebuilding Preview files works?

Thanks

No problem....just took me a little while to figure out what was going on....some really strange things.  I should have known better before I changed the Preview Folder's name.

Good point, too, about backing up the Previews.  Have to look into how I can easily do this.  Right now, I have the entire Pictures Folder backed up to that external drive.  That has many folders, including the Lightroom folder, which has the Catalog and Preview files/folder in it.  I should be able to turn off the subfolders for backup.

I'm just rebuilding previews of individual folders right now, just to make sure things look right.  If things look good, then tonight before I go to bed, I'll rebuild the remaining previews.

One last question.....does every single image in a catalog have its own, dedicated preview file?  If so, is there any rhyme or reason as to the preview file names?  I've noticed that in individual sub-folders (for example, "6/6ADA/") there often is just one preview file, but sometimes, there are 2 or more files.   Why would there be more than 1 Preview file in a folder like this?  Just curious, more than anything else.

Thanks again.

Thanks again for your response.

Just another quick update....last night, and over night, I recreated more previews....did it main folder by main folder.  Everything seemed to go well over night, and I have about 25% left to do with on large folder remaining.

I do have another "last" question about the preview files.  If I delete a photo from a catalog, is its preview file(s) removed as well?  Or, if I move photos from one folder to another, rename them, or make some change of this nature, are new preview files created, and if so, are the old ones deleted?

I guess what I am trying to get at is, is there a routine you might recommend about how to rebuild the preview files periodically?  I periodically just remove old catalog backup folders....typically, at most, I keep just one month at a time.  So I'm wondering if it makes sense to do this with the preview files in order to clear up some disk space?

Thanks.