Did you try a clean install of D2:ED and then FoV? (uninstall FoV/D2:ED, reboot, make sure there is nothing left in the D2 folder (saves are stored elsewhere), then install D2:ED and FoV)
In XP the saves are in the folder
C:\Documents and Settings\ %username% \Local Settings\Application Data\Divinity 2\Savegames
or in Vista / Win 7
C:\Users\ %username% \AppData\Local\Divinity 2\Savegames
You may need to set Windows Explorer to show hidden files and folders (
XP, Vista,
Win 7).
BTW, on an unrelated note, what is the download size of FoV? That isn't listed on the Larian Vault product page.