Problem mit Oregon300

Sorry I need help and my english is not good.
I loadet with openmtbmap.org Great Britain on my PC but when I want to open this I got a message …Installer integrity check has failed…more at http://nsis.sf.net/NSIS_Error.
But the Swiss map was no problem. The file is only 2 MB is this OK?
Than I lodet Great Britain wit open street map and now I have it on my Map Source.
When I mark the map and say, send it to my Oregon 300 it need a long time but finaly there is a message, is OK
When I start the Oregon the say… Cant Autenticale Maps, an even part of mx Topo Austria are gone.
Garmin Graz, Austria, say thats a problem with open street map sorry!
What shall I to?
Please help.

“The file is only 2 MB is this OK?” Surely not.
I think something went wrong when the map was created. You could try velomap (ftp://ftp5.gwdg.de/pub/misc/openstreetmap/openmtbmap/velomap/), the file there is some 300 MB which looks OK.
[Edit] By the way, there are many forums in other languages, e.g. German: http://forum.openstreetmap.org/viewforum.php?id=14 [/Edit]