Comment 1 for bug 400073

I'm having a similar problem (don't know if it's the same as original report since there's not much info there, but the title sounds just right).

I'm on winxp sp3, trying to run wubi from a usb stick containing the ubuntu netbook remix image, which comes with wubi.exe in the root directory. The image itself is ok (no errors found during check, and it boots from usb with no problem). However, when I run wubi.exe, nothing happens. More specifically, I looked at the task manager and saw a process named pyrun.exe as well as another temp-named process with 'py' in it, they start and then die off silently after a second or two, and that's it, nothing happens, no message or error or display of any kind.

I found the wubi log file, which showed the following error (there are no additional log lines after these):

...
08-01 15:38 DEBUG Distro: checking whether D:\ is a valid Ubuntu CD
08-01 15:38 DEBUG Distro: info=Ubuntu-Netbook-Remix 9.04 "Jaunty Jackalope" - Release i386 (20090421)
08-01 15:38 ERROR root: unpack tuple of wrong size
Traceback (most recent call last):
  File "Z:\home\evan\bzr\wubi.trunk\build\wubi\files\lib\wubi\application.py", line 54, in run
  File "Z:\home\evan\bzr\wubi.trunk\build\wubi\files\lib\wubi\backends\common\backend.py", line 161, in fetch_basic_info
  File "Z:\home\evan\bzr\wubi.trunk\build\wubi\files\lib\wubi\backends\common\backend.py", line 665, in find_any_cd
  File "Z:\home\evan\bzr\wubi.trunk\build\wubi\files\lib\wubi\backends\common\distro.py", line 85, in is_valid_cd
  File "Z:\home\evan\bzr\wubi.trunk\build\wubi\files\lib\wubi\backends\common\distro.py", line 156, in check_info
ValueError: unpack tuple of wrong size