Blank site after copying to another folder location

Hi

I’ve just copied a site from my development area to the clients live domain and now the site is blank – can’t even get into /wp-admin.

The site is on the same machine (i.e., same host), all I’ve done is copy the files to another location.

Here’s what I did (all file copies done by FTP):
1. Copied all the files from the dev area to my local machine
2. Then copied all the files to the client’s site – which is on the same physical machine as the dev area. i.e., same ISP, same machine
3. Tried to browse the site -> blank site
4. Tried to get into wp-admin -> blank site
5. Realised I forgot to update the Settings. So I logged back into the site in the dev area, changed the WordPress address and the Blog address to the client’s domain name.
6. Tried to browse site and log into wp-admin -> blank site still.

I’ve tried:
– checked the wp-options table in the database to verify the site_url was correct. It is correct.
– increased memory size in wp-settings.php from 32M to 64M – still blank.
– checked wp-config.php to make sure the database and user names were correct – they were, I had not changed them since copying so that was expected.
– renamed the plug-ins folder, created a new empty plugins folder – still blank.
– tried loading a plain html file. That was ok so I know the virtual host is fine.
– created a simple php file that just prints hi from php at this URL and that runs just fine.
– moved dev area site into another folder to ensure the server wasn’t looking in the old location. Still blank.

I’m assuming it’s not memory or plug-in related because it was all fine and the machine is the same machine, the site is just in a different location.

Is there a way to switch WordPress into debug mode so that errors are displayed?

Any suggestions would be greatly appreciated.

Thanks
Jonno