I just got the Bon Voyage package a few days ago. It has worked fine, but now every time I try to run Sims, a box comes up saying, "The Sims 2 is already running!". It is obviously not running. I don't want to uninstall and reinstall the game because that will delete all my files. Any suggestions?
First, check your task manager (ctrl-alt-del) and make sure The Sims 2 and the process Sims2EP6.exe aren't running. If you have FreeTime make sure the process Sims2EP7.exe isn't running. End the process if it is running. Those instructions are for Windows XP - I don't know how to do that on Vista.
Uninstalling and reinstalling, which only should be done as a last resort, won't get rid of your saved games if you make a back up first. If you made a back up before installing Bon Voyage (like the installer strongly suggests) then do the same thing again. If you didn't make a back up then if you care about your neighbourhoods you should make a back up very so often and always always make a back up before installing a new expansion pack. This guide explains how to make a back up: http://www.sims2wiki.info/wiki.php?title=Game_Help:Back_Ups