There maybe a corruption in that file...
Go to your shared/saved folder (outside of Limewire) you will find this folder by clicking on one of your files in your LW library and clicking explore...
If you get a lock up or an error when trying to do this, use your computers search and find the offending file and delete it...
If you can get into your shared/saved folder right click on the file and scan it with your AV, if it's all good keep it if not delete it...
Another tip to try is sticking with avi files and check them with Bitzi before downloading...
How to use Bitzi Web Lookup .. & How to use Magnet Links & Direct Connect/Browse/Chat