We have had the same issue with the blank plesk page upon install. I beleive it has do do with the errors found in C:\Program Files\SWsoft\Plesk\admin\logs\ssl.log
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[Sat Sep 10 06:37:22 2005] [info] Connection to child 24 established (server localhost:8443, client 127.0.0.1)
[Sat Sep 10 06:37:22 2005] [info] Seeding PRNG with 0 bytes of entropy
[Sat Sep 10 06:37:22 2005] [info] Initial (No.1) HTTPS request received for child 24 (server localhost:8443)
[Sat Sep 10 06:37:45 2005] [info] (OS 10060)A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. : SSL input filter read failed.
[Sat Sep 10 06:37:47 2005] [info] Connection to child 24 closed with standard shutdown(server localhost:8443, client 127.0.0.1)
[Sat Sep 10 07:02:11 2005] [info] Connection to child 24 established (server localhost:8443, client 64.34.130.251)
[Sat Sep 10 07:02:12 2005] [info] Seeding PRNG with 0 bytes of entropy
[Sat Sep 10 07:02:12 2005] [info] (70014)End of file found: SSL input filter read failed.
[Sat Sep 10 07:02:12 2005] [info] Connection to child 24 closed with standard shutdown(server localhost:8443, client 64.xxx.xxx.xxx)
[Sat Sep 10 07:02:13 2005] [info] Connection to child 24 established (server localhost:8443, client 64.34.130.251)
[Sat Sep 10 07:02:13 2005] [info] Seeding PRNG with 0 bytes of entropy
[Sat Sep 10 07:02:13 2005] [info] Initial (No.1) HTTPS request received for child 24 (server localhost:8443)
[Sat Sep 10 07:02:29 2005] [info] (OS 10060)A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. : SSL input filter read failed.
[Sat Sep 10 07:02:31 2005] [info] Connection to child 24 closed with standard shutdown(server localhost:8443, client 64.xxx.xxx.xxx)
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This occured when I attempted to go to
https://<SERVER-IP>:8443 instead I just used
https://localhost:8443 and it works!