Cannot get hotstart 1.7 installed

Hi. I previously had the 1.6 hotstart installed. I dropped and recreated the MySQL DB, deleted all the Joomli files in the directory, and did a fresh install of the 1.7 hotstart.

All goes perfectly up to step 6 Configuration. Even sample content reported as installed successfully.
When I click next, it just gets stuck on the spinner / loader graphic and never finishes. I left it for an hour.

I thought perhaps it finished anyway, so I deleted the installation folder and tried to navigate to the site, but it says there was no config file detected and no installation folder, so it exited.

Any ideas as to the problem?

Installed on Windows.

Thank you.

Have you tried to delete database first?

Yes. I have completely deleted and recreated the DB.

"but it says there was no config file detected "

- do you meant IIS throws error about web.config missing or joomla throws error?

No, Joomla.
If I tried manually deleting the installation folder, after it got stuck on step 6, and then reloading the page.

At that point Joomla gave the error that there is no config file detected and also no installation folder, and that it exited.

The pre checks were all fine and config file is writable.

PHP Version >= 5.2.4 Yes
Zlib Compression Support Yes
XML Support Yes
MySQL Support Yes
INI Parser Support Yes
JSON Support Yes
configuration.php Writeable Yes

Directive Recommended Actual
Safe Mode Off Off
Display Errors Off On
File Uploads On On
Magic Quotes Runtime Off Off
Register Globals Off Off
Output Buffering Off Off
Session Auto Start Off