If you're familiar with regedit,you could go into the registry to have a look,if you wish.
Go to Start,type regedit,and doubleclick it.
Navigate to KEY_LOCAL_MACHNE\SYSTEM\CurrentControlSet\Services\Eventlog\Spybot - Search and Destroy\
Rightclick the Spybot Search and Destroy key(should look like a folder),and follow this to back it up,just in case:
http://antivirus.about.com/cs/tutorials/ht/regkey.htm
(You don`t have UAC turned on,so the above instructions should work.)
Then,rightclick Spybot - Search and Destroy again,and select Permissions.See if the username that you are installing with has full control.