Create a shortcut for your shared folder on your desktop. Leave the folder where it's at.
Not sure about the other problem. Check and see if LW is using up all your system resources(Ctrl+Alt+Delete). You may need to adjust the settings in LW, and/or try deleting the LW preference folder, points 2 and 3 in this thread:
Fixes for Limewire when LW isn't operating as it should!
You could also try using another media player.
VLC media player is a good one that has the codecs built in and will play most file types.
Go to this thread for more on info:
CODECs list for Movies /Alternate players / Video help forums