User Account with Admin rights does not really have admin rights

I'm the only user of the computer and supposedly have Admin rights. However, cannot manage computer or install any software. I activated the hidden Administrator account and created a new user account with admin rights, but same result, the new account cannot perform admin tasks. All this after my computer was infected with 3 instances of Trojan-Downloader.Java.Agent.en (as reported by Kaspersky - Bavarian/Saxonia/Silezia) and 1 Folders Infected:
C:\Users\Michael\AppData\Roaming\SystemProc (Trojan.Agent) -> Quarantined and deleted successfully as reported by MBAM.
All user accounts work FINE in safe mode (they have admin rights) but do not have admin rights when Windows starts in normal mode. Any suggestions on how to fix this? Thanks in advance.

On a related (or unrelated?) note: IE8 cannot connect to secure sites, shows cypher strength 0 in normal mode with Kaspersky firewall running, but connects without issues in safe mode (Kaspersky firewall off). Perhaps settings of Kaspersky were affected by the trojans?

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