I’m having this problem, too in IE8.
Used this post to cobble together a solution:
http://forum.khairul-syahir.com/graphene-support/nextgen-gallery-thumbnails-smushed-when-inserted-onto-page#post-7871
Here’s what I did:
Edit your NextGen plugin nextgen-gallery/css/nggallery.css file
Add this style setting
width: auto;
to
.ngg-gallery-thumbnail img
Works great.
Suggestion: incorporate this change into the next update to the plugin.
Thank you WayneM1 for that information, works great!
Thanks so much – worked perfectly!
Follow up…
Although the fix I posted about above works fine, it is susceptible to being “un-fixed” if there is an update to the plugin that does not incorporate a fix for this problem.
With that in mind, you can also effect a change to the CCS for this plugin by using another plugin “My Custom Css” (http://wordpress.org/extend/plugins/my-custom-css/). This is a very useful plugin for making any kind of CCS custom styling you want/need. It saves any added custom CSS in a separate file that will not be overwritten by theme or plugin upgrades. I needed to add some custom CSS for another different fix, and found this gem of a plugin. I highly recommend it.