All images are displayed at once.

I'm having the exact same issue. I've unzipped the plugin to sites/all/nivo-sider and installed JQuery Update Module, as well as Libraries. All modules are enabled, and I've tried setting the JQuery version to 1.7 and 1.8. Caches have been cleared repeatedly. My slideshow keeps appearing as just a list of my pictures - basically it's just displaying them all at once. You can see my site here: http://bioinovatisse.podserver.info/. Any help is greatly appreciated!

@chunkyfoo
I've inspected your site and the console shows "TypeError: $(...).nivoSlider is not a function", this is probably because the nivo slider module cannot access the nivo-slider jquery plugin you are including in your libraries folder. Make sure that you've placed the plugin there. Just to make things clear I'm writing the steps here:

1. Download an install Libraries API - 2.x (https://drupal.org/project/libraries)
2. Download an install Jquery update (https://drupal.org/project/jquery_update)
3. Download nivo slider jquery plugin (http://dev7studios.com/nivo-slider/)
4. Extract the folder, you can see there are two subfolders inside the main folder, one is for MACOS, don't use this...copy the other folder, though this folder's name is already "nivo-slider" but if its not rename it to nivo-slider, and place it in sites/all/libraries folder(create this folder if it doesn't already exist)
5. Flush the caches

Hopefully this will solve your problem

Thank you! I created a new site using the same server (since the first one wouldn't let me delete some of my files) and your guidance worked. The slideshow works well now.

My pleasure! Since it seems to solve your problem, I'm closing this issue