[raidzero]

actually if are up to it you could edit \windows\titanium_480x640.cpr and also 640x480.cpr and replace all "" with "tahoma".
when you click cancel it goes ahead and replaces all occurences of whatever font you have with nothing, so the error comes from when it does that it goes to replace again, the replace command needs two arguments and it only gets one because the variable "source" is blank...