when you have a dir, that is not chmod777, for the data on Windows, the page re-appears, but it doubles the ammount of s

so the first time its

and the second its \

\\\\

eventually it says cannot find \\\\\\\\\\\\\\

no biggie.

BUT

that info is saved in the session, so when you re-try the install its says something like:

PHP ERROR: \\\\\\\\ cannot be found, and no form is shown, so you have to open another browser, and set the moodledata dir to 777.