for a while we've been having problems with generating PDF that contain utf8/non-latin tyle characters - accented/euro symbol etc..
i've just put in a small fix onto our demo site http://www.simpleinvoices.org/demo
if you have had PDF and non-latin character problems please login to the demo site and create some new invoices and try to PDF - let us know if it now works or still has problems - and which characters you used
Noet: this fix will mess the display of previously entered accented characters. They will have to be fixed manually.