Blank screen w/DisplayLink 1.7 caused by bad libusb in linker
 

I managed to diagnose and correct this one myself. Recording here for posterity.

I did a clean install of 10.6.8 on my MacBookPro. After installing the 1.7 driver, the display remained blank (I had previously been using 1.6 b4, I think). I enabled verbose debugging in the DisplayLink Information application and then looked in the Console.

The driver was attempting to load /usr/local/lib/libusb-0-1.4.dylib and failing. Over and over and over and over again. Looking in /usr/local/lib, I found libusb-0.1.4.4.4.dylib but no libusb-0.1.4.dylib.

I symlinked 0.1.4.4.4 to 0.1.4 and then the display started working again.
Looking at a backup of my pre-reinstall drive, I see that that symlink did exist before, though I have no idea how it got created.

Thanks for your post. You fix is correct, most likely a previous libusb installation was already available in your system. We will improve our installation script. Thanks

libusb link broke after XCode install
 

I wanted to bump this post as I was having the same issue and discovered the same fix. ACtually my /usr/lib/libusb.dylib link was pointed to a file called "v". Everything had been working fine until I installed the Xcode command-line tools I believe.

J