Sounds like your client and the game server got out of sync due to lag. Once the client and server get out of sync, your character looks like it is walking, but you can't move, and macros mis-fire. I got this a lot last fall and winter before the servers were moved to the cloud.
The lag may be caused by: A) UO servers - not likely with the new servers; B) Your ISP - very possible but you can't do much about this; C) Your computer.
I found that a lot of lag was caused by my computer - all the Windows programs trying to update when I was playing UO. You can manually try shutting off each program and stopping them from updating, but it's a pain and you might miss a security update if you forget to turn it back on. Windows, Firefox and Adobe programs fall into this category.
There is a free program called
Razer Game Booster that will turn off updates and unloads programs from memory when you start a game, and then restarts everything for you when you quit the game. This program does not intercept game packets or do anything else, and is completely legal. It does have a similar sounding name to other not-legal programs, but this program is not in anyway related to those. It will find most games on your computer automatically, but I had to add UO manually (easy to do). Try it, it may help, and if it doesn't help, just remove it.
Here is the download link:
http://www.razerzone.com/gamebooster
