Try making a second iw5m.dat (so you can keep the old one) and get the new one called iw5m.dat - copy and name it iw5m.exe, that's how I run it, but as kenshin said it has been crashing a lot
Sorry, I was rather vague.
Copy iw5m.dat into the same directory, it will create a new on called iw5m - copy.dat rename the copy to iw5m.exe run it through that and it should work (it worked for me)