I got around it by making a windows script which closes mp, runs webepg, then restarts mp - then i scheduled the script. works ok-ish.
set Services = getobject("winmgmts:root\cimv2")
Set oProcess = Services.Get("Win32_Process")
strQuery = "select * from win32_process where name ='mediaportal.exe'"
Set Procs = Services.ExecQuery( strQuery )
for each proc in Procs
proc.Terminate()
next
Set WshShell = WScript.CreateObject("WScript.Shell")
Return = WshShell.Run("C:\Progra~1\Teamme~1\MediaP~2\WebEPG.exe", 0, true)
WshShell.Run "C:\Progra~1\Teamme~1\MediaP~2\mediaportal.exe"