LR4 error when reading from its preview cache, needs to quit

Question

I'm getting the above message.  Lightroom says it will attempt to fix this problem the next time it launches,
requiring me to click OK and the program closes.  When I relaunch it, I see the same message.
I'm on a PC w/ Win7; I updated LR4 with the 4.1 download recently to enable it to read the 5DMarkIII raw files.

Answer 1

From: "Steve from Maryland
I am having this problem regularly now on my laptop (SSD HDD and 64 bit
Win7Pro). I have erased the cache multiple times (BTW- you have to stop
textextractor.exe to be able to do this- more on this below as well). The
corruption keeps happening and I don't know why. Anyone????
Not sure what cache you are talking about. LR only refers to two 'caches' -
the acr cache which stores part-rendered images to speed up rendering in
Develop, and a video cache which does something when you use videos. The
catalog and previews are stored in another folder, along with a previews.db
and a rootpixels. db which store info on the previews.
If you are having trouble as you describe, you need to delete the previews
folder (including the two .db files) just leaving the catalog. Then you need
to clear the acr cache (under Edit/preferences/File handling/camera raw
cache).  Then regenerate all your previews in LR (select your main parent
folder, and tell it to build all previews). If you have a lot of images,
best to do this overnight.
Then all the various caches, databases, previews, and catalog should now be
in sync again, and you shouldn't see that error.
Not sure what textextractor is but if it interferes with LR, I'd get rid of
it.
Bob frost