500- Internal Server Error & open_base_dir restiction

Long story short, I was trying to move my WP site from a development subdomain to my main domain and obviously screwed something up so I have restored from a backup an I am now getting an HTTP 500 error.

This is a windows server running PLESK.

I have the following error from the hosting company:

PHP Warning: require(): open_basedir restriction in effect. File(./wp-blog-header.php) is not within the allowed path(s): (C:/Inetpub/vhosts/***.com\;C:\Windows\Temp\) in C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php on line 17 PHP Warning: require(./wp-blog-header.php): failed to open stream: Operation not permitted in C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php on line 17 PHP Warning: require(): open_basedir restriction in effect. File(./wp-blog-header.php) is not within the allowed path(s): (C:/Inetpub/vhosts/***.com\;C:\Windows\Temp\) in C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php on line 17 PHP Warning: require(./wp-blog-header.php): failed to open stream: Operation not permitted in C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php on line 17 PHP Fatal error: require(): Failed opening required ‘./wp-blog-header.php’ (include_path=’.;./includes;./pear’) in C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php on line 17

I can see from the Plesk panel that open_basedir is set to
{WEBSPACEROOT}\;{TMP}\

and I would have thought that the {WEBSPACEROOT} folder of C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs\index.php would be C:\Inetpub\vhosts\***.com\subdomains\dev2\httpdocs and not C:\Inetpub\vhosts\***.com or am I just reading the error incorrectly?

Is this something that I have done wrong or is this a configuration/permissions issue that my hosting company needs to address?

Thanks

Just by way of additional information, I have full access to the wp-admin panel except for the permalinks page which also gives the 500 error.

Also if I set the Debug option in wp-config to true I then loose access to the admin panel until I set debug back to false.

Anyone have any ideas to help me, please?