

Look through that addon's options to see if there's a way to stop it from hiding the Blizzard frames. DisableAddOn("Blizzard_CompactRaidFrames") - then you've found the problem. If you see any lines that appear to be disabling a Blizzard addon - eg. Sorting the results by file name will help you ignore them. You'll get about a billion matches on all the copies of AceAddon-3.0 in various addons. Search for "DisableAddOn" in all *.lua files in your AddOns folder (and subfolders). If you don't already have a program that can search for text inside files, grepWin is a good one. If you're not afraid of seeing Lua code, you can take a shortcut.

If you have no idea which of your addons might include such a feature, here's how you can figure it out: It's most likely an addon that provides its own party and/or raid frames, or an addon whose specific purpose is to hide the default UI's party and/or raid frames. However, before you do that, you need to figure out which addon is disabling them, or it will just do it again. You can't turn them back on via the addon list, but you can turn them on by calling an API function in addon code (or in a macro). Most likely some addon has disabled the Blizzard addons that provide the default UI's compacty party and raid frames.
