Close Minecraft. Go to wherever your mod pack is located on your computer, open the saves folder, delete the folder named NEI. Launch Minecraft again and it should be fine.
If the freezing goes away then that freezing is normal. When you search for what items can be created from an item NEI searches through all the recipes which can take a little while. If it does not do as arentol suggested. Please post a console log in debug mode to pastebin.com if neither of these fixes the issue. Look here for help with the log.
