Vista - Problems Occurring After Turning User Account Control ON

Hi everyone,

I've had User Account Control turned off for a while now, mostly because
it's really annoying when Vista asks if I really want to do everything. I
just turned it back on a day or so ago and now everything has been acting up.
I will try to list all the weird things that have been happening since I
turned UAC back on:

1. When I log onto my computer after putting my password in, I am greeted by
a black screen with only my cursor visible. Then, I go to CTRL + ALT + DEL as
usual and try to Run explorer.exe (this has happened before but not on
startup for me) but it doesn't work. Then I realize that I have to go to
Processes and press the button that is now there, saying Show Processes For
All Users. It's usually a checkbox that's always checked but now I have to
press that button most of the time when using the Task Manager. Then, after
pressing that, I am able to start explorer.exe.

2. My Aero is apparently shut off permanently. It seems like it's been set
to Windows Basic, where nothing is transparent but it is still all Vista-y. I
went to Control Panel and tried to set it to Aero instead of Windows Basic
but the preview box for Aero looks like the one for Windows Basic (and I know
that picture isn't frozen there because all of the other types of Windows
looks show up, like the older looking ones). By the way, it's already set to
Aero, even though the preview box looks like Basic. I would like to know how
to fix this, and I know it's not my graphics card because it's a 5.9 for
using Aero (and I did test again, and the test still says the same number).

3. Sometimes when I try to open iTunes, this message starts up like it's
trying to install iTunes, then a bar fills up twice and the program opens.
It's kinda annoying.

4. Explorer.exe as of now will not start working correctly again. Usually
when it starts acting up I can go to Task Manager and Run explorer.exe and
keep trying to open My Computer, and after a few tries the taskbar and
desktop will stop disappearing and everything will work fine. Now I think
I've tried this about twenty times and it's still doing going away when I tyr
to use My Computer or any explorer-related thing.

That's all the weirdness I can think of as of this moment, and I'm scared as
to why my computer would just start acting up for no reason like this. It was
really working fine before I turned UAC back on, so I don't think I got some
kind of virus or something. If someone could help me with this issue it would
really make my day. Thanks for your time.

Can someone please help?