Lightroom 3 will not import any images

Question

[I replied to another thread, but it doesn't seem to be coming up at the top of the post list when I update my information, so I'm reposting in the hopes that someone will notice and offer some helpful advice, as this is rapidly becoming infuriating.]
I'm running LR3 on Mac OS 10.6.4.
I put my SD card into my iMac's SD card slot, and tried to import into LR3, but got an error that all of my new files were not imported because they "...could not be read (17)".  They can be read just fine by GraphicConverter and Lightroom 2.  I shoot RAW+JPG and LR3 will not import either version (e.g., if I remove the .CR2 files from the SD card, LR3 won't read the .jpgs either).  I also put the SD card into a reader (instead of into the iMac's SD card slot) and that didn't work.
I copied the RAWs to the Desktop and tried to import from there, but in that case I get a message that the import operations were not performed because "a file could not be copied to the requested location (34)".
I imported images from this SD card on the 5th, and I haven't formatted it since then.  The only thing that's changed that I know of is the Mac OS update, but I would expect that if that were the problem, I wouldn't be able to read these files anywhere (i.e., GraphicConverter).
Update:  I've now tried another SD card, and a CF card, and LR3 will not import any of the files on them - I get the same "...could not be read (17)" error.  I have repaired disk permissions, and I've trashed the Lightroom 3 preferences.
Update #2:  I've deleted and re-installed Lightroom 3, and I still cannot import any new images.  Lightroom 2 continues to import just fine. 
Anyone have any suggestions?

Answer 1

OK, I _think_ I have the cause & cure.
Cause:
Canon says the software [firmware?] bundled with the Canon Rebel XT  "is not fully compatible with the latest version of OSX." I can continue to automatically bring up iPhoto or use ImageCapture, in any case.  Thanks, but I want LR3.  Canon recommended that I set the controls in ImageCapture to specify opening LR3 when a camera is detected.  I did, but it was doing this before, so I saw no difference.  Also, I'm not sure it was doing it reliably, before or after this change.
This software incompatibility might explain why the Canon Rebel XT was not loading into LR3, but would not explain why it was not recognized by the Finder to add to the Devices list.  The Canon wouldn't get added to the Devices list in OSX 10.4.11, either.
ImageCapture could easily see the images on the camera, and could copy them to a HD without difficulty.  But it's not LR3, and nothing convinced the Finder to add the camera to the Devices.
Cure:
What I did find, eventually, as a method for persuading LR3 to import properly is this:
I set ImageCapture to open itself when it recognizes a camera.
I jack in the camera, and ImageCapture opens.
THEN I open LR3.  It comes up with the present images in the library.
I _click_ on the Import button (lower left), OR use the keyboard command (cmd-shift-I).  It opens the import display, _with_ the images from the camera.
I set the LR3 import settings as I want them - I Copy the files, change file names, presets, etc. as desired.  (I make a habit not to erase the camera files, until all is said and done, and the camera is disconnected from the computer.)
I click the Import button, and it does!
SUCCESS!
If I have it open ImageCapture first, that seems to persuade LR3 that images are on the camera.
Sometimes iPhoto accomplishes the same end, but I'd rather not launch that - subsidiary issues.
I went through this sequence a number of times, starting from neither software open.  I tried different sequences - LR3 then ImageCapture, camera first or last, etc.  The above sequence worked reliably; the others' responses confused me.
Those of you with similar Canon uploading problems, see if this helps any.  If you don't have ImageCapture, try it with iPhoto instead.  Just open it first.
sandrift71, does this answer your original question & resolve the problem for you?
Message text clarified - edited by: Jay_Warner