Postfix install caused Plesk Panel to become blank

[SuperBadConchord]

Yesterday I moved from qmail to postfix, but when I login to plesk from the web interface I am shown a blank white screen. I installed postfix from the web interface (through the email server setting) and now cant get back in. Can anybody suggest a reason and a solution. If you require more information I can provide it.

 

[IgorG]

Have you tried bootstrapper repair procedure?

 

[SuperBadConchord]

Just done that but same things happening