Updated to View 7.5
Now, when connecting through a web-browser, we see the following (screenshot) instead of the login/password input window. Rebooting the servers does not help, cleaning the cookie also does not help.
There could be a number of different causes for this issue. In a case like this, a dive into the logs and system events is needed. Do you have a support contract with VMWare? If so, I would create a support ticket to look into this further.
Is this happening across all browsers or is it just a specific browser? If it is only happening in Chrome, please take a look at this site below.
Eliminating the browser to be the issue is good idea.
You could also just uninstall and reinstall 7.5. I've done it plenty of times as the upgrades are not always 100%. Be sure to take snapshots and/or backups of the VM and environment. When uninstalling, DO NOT REMOVE the ADAM DB. It's what contains everything related to your View environment.
Also, do you only have one connection server? Adding in a replica server is recommended for redundancy. You could point to that specific server and test the web portal.
Hope that helps.