According to AgeCommunity these are the bug fixes included in the patch:
- CLIENT FIXES
- Update to the patching process which should address difficulties experienced during the autopatch process.
- Resume button added. A dialog is now displayed when a user pauses the game.
- NETWORK AND ESO FIXES
- Changes to Games List functionality. The list is pulled down once on initial login and can be updated by pressing the Refresh button. Automatic updates will no longer occur.
- Quickmatch now uses only standard maps.
- Home City level now displayed on the Game Start screen.
- Clan tags added to the Advanced Game Setup.
- Fixed an issue with clan chat not being displayed.
- Fixed a game pause issue when a resigned player remained in game.
- Removed the exploited ability to split the military and economy scores.
- Timeout added to Vote Dialog box.
Before installing the patch manually see if you are not able to update the game through the help menu. Click Help and Tools then click Update Game to get the latest patch, which updates the ESO game browser, the patch installation process, and more. If this didn't work then you should download the standalone patch here: Patch 1.04 (released on 19-Jan-2006).