My internet explorer is having problems

I am running a Vista Home Premium Operating System, 32 bit. My internet explorer is giving me trouble. It redirects me to other site pages i haven’t commanded it to. I can’t defragment my drive C, it blocks any attempts I can’t update my anti-virus, it blocks the updates I also block me from turning the firewall on Recently it has been freezing, not opening other search pages and it restarts frequently I tried to update it and this was the error message i got “To install updates from this website, you must be logged on as an administrator or a member of the Administrators group on your computer. If you use Windows XP, you can see if you are an administrator by going to User Accounts in Control Panel. Note: If your computer is connected to a network, network policy settings might also prevent you using this website. Contact your system administrator for help with updates.” I really don’t understand this because i am logged in as an administrator. The network settings are not the problem, i have checked them and did some troubleshooting, and confirmed they are ok. I am afraid something bad has happened and can’t figure out exactly what it may be. Please help me fix this. Martin
