I'm not a Vista user, so apologies if this advice doesn't work

Try right clicking on the LW desktop icons of the other 2 accounts > run as administrator.

Or have a look at the thread below & see what this Vista user did (even though their problem was slightly different to yours).
http://www.gnutellaforums.com/304737-post4.html

Also, make sure that all accounts are using different port numbers in LW. To check/change port numbers, in LW tools > options > advanced > firewall config. You can change LW's listening port on that page, just click apply > ok to save a change.

Unless you've used really old versions of LW in the past, you won't have a preferences folder named .limewire. The folder changed location in LW version 4.9.34. For newer versions, the folder's named LimeWire & should be located in C:\Users\your username\AppData\Roaming\LimeWire