Your log file is in %APPDATA%\MMOI\mmoimgr\log.txt on windows.
Fair warning: It's huge.
This may help you identify which addon it thinks it's installing. You should look for lines similar to the following:
Code:
MDD> 05-06-09 08:37:10.624 - [MMOUI Manager - World of Warcraft] Detected addon ID for Clique: 5108
If it says "0" then it could not be found on WoWI. Note that you will need your log verbosity set to "DEBUG" (I believe this is currently the default -- if not, you'll find this in tools->options->global)