Getting 'Warning: require' errors all of a sudden

All of a sudden I’ve started to get Warning: require errors on both the WP Control Panel and on the website itself. Examples:

panel error
Warning: require_once(./admin.php): failed to open stream: No such file or directory in \\NAS-001\WINSPACE004\10-horneconstruction.ca\www\wp-admin\edit.php on line 10 Fatal error: require_once(): Failed opening required ‘./admin.php’ (include_path=’.;D:\php\includes;D:\php\PEAR’) in \\NAS-001\WINSPACE004\10-horneconstruction.ca\www\wp-admin\edit.php on line 10

webpage error
Warning: require(./wp-blog-header.php): failed to open stream: No such file or directory in \\NAS-001\WINSPACE004\10-horneconstruction.ca\www\index.php on line 17 Fatal error: require(): Failed opening required ‘./wp-blog-header.php’ (include_path=’.;D:\php\includes;D:\php\PEAR’) in \\NAS-001\WINSPACE004\10-horneconstruction.ca\www\index.php on line 17

It’s like all of a sudden any path name with a ‘./’ at the beginning of it is no longer valid.

Any ideas? I’ve tried a fresh install of my wp version.

Could this be a server config issue? Any suggestions would be appreciated I’ve spent hours trying to source a fix.
Thanks