I have installed Appian 7.5 on my local system having Windows 7. Tempo & Des

Error Screenshot

Looking at your logs, I see a lot of errors that are indicative of a misconfigured system (errors with WEB-INF/conf/security/spring-security-05-web-api.xml, IPC errors indicating that communications with the engines is failing, etc.).

Maybe those are from earlier and resolved those though, because I don't think you could have reached this interface with those errors.

The one thing I do see is that you are attempting to access the admin console as the Administrator user. Use a different user of type System Administrator instead. The Administrator user is specifically prohibited from accessing the Administration Console in order ensure that all changes can be traced to a specific named user rather than a shared account. (forum.appian.com/.../Appian_Administration_Console.html

The interface should have displayed a friendlier message to you about the error rather than showing you that "Unrecoverable" error dialog. There is either some bug that caused that message to not appear as it should have or it's a result of a latent misconfiguration.

I have created a "System Administrator" user admin and then trying to login and access admin console.

1. Your log shows you were using the account with user name "Administrator"

2014-08-13 15:51:13,571 [http-/0.0.0.0:8080-5] ERROR com.appiancorp.sailapp.urlrewrite.AdminApplicationFilterForwarder - Unauthorized user, WebServiceContext[Administrator : null], attempted to access /suite/admin/. User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko

Does the log show that because you indeed tried several times to test with this account?

3. What is the exact username you tried with that showed you the pop-up from the screenshot?

4. Can you please verify the conf.suite.SERVER_AND_PORT setting is properly set and matches your URL as explained here: forum.appian.com/.../e-117002 this will basically prevent from moving from one screen to another and not that pop-up bit still something to check.

5. Can you click the Signout button, delete your browser cache and then try again with the test account? (Remember, DO NOT USE "Administrator")