When I tried to run WUBI to install Ubuntu on a Windows XP system, it failed without any warning. I finally found the log file, and discovered that WUBI fails silently if it finds an ISO with the file size that it expects to find, but without the correct content.

The only way to solve this was to run WUBI multiple times, and each time check the log file to find which ISO file it tried to load - and then rename the file to another extension (for example, .ISO--) so that WUBI would not try to load it. After renaming three such ISO files, WUBI eventually ran.

Perhaps WUBI could at least post an error message explaining why it did not run. That would be better than failing silently.