Hi There,
I have asked this question on other forums wothout hearing a response as yet.
Is there anyone else out there running a mac pro on os x 10.7.5 having difficuties getting Lightroom 5 to read images? The mac pro I am running can't be upgraded further as Apple deems it past its use by date...2007! Interestingly, the files can be imported to my (internal)hard drive and opened just fine, it's just when I try to access them off the external hard drive, i get this displayed in the top right corner an 
with the msg, "Lightroom has encountered problems reading this photo, you will not be able to make adjustments to this file."
I first discovered this issue when the 4.4 update came earlier this year(2013). I updated this on my Mac pro running OS x 10.7.5 and upon updating the library file there was an error file that the NEF and JPG files
Furthermore, I created a new catalogue where the same issue arose. I also thought that this might be resolved when updating to Lightroom 5...not yet??
I have also tested this on my Macbook pro running os x 10.8.x(latest) with no issue reading the same catalogue on both LR4.4 and LR5 from the same external hard drive without issue.
In the meantime I am having to revert to using the older LR4.3 as this works fine on the Mac pro desktop as this is the main computer i use...at the moment!
Can someone assist me with a suggestion as I would prefer to have lr5 as my preferred tool across all platforms?
thanks in advance,
Matt