Aero and various other effects have been disabled, no idea why

[Mooe94]

This morning I noticed that the aero effect was disabled, so I went into personalization and checked it out. I can't find anywhere to enable it anymore and some other effects have been disabled such as when you minimize a window there should be a fade of some sort.
I have restarted the computer numerous times, terminated various processes but alas no success.
The only thing I have done recently is playing Max Payne 1 and two, and installing Mafia. (I had no internet for the past two days, so)

I have tried terminating dwm.exe and enabling it again, but it doesn't show up again after I have ran it.
Anyone know why this is happening? As far as I know nothing is wrong with my graphics card and I haven't been around any particular settings.

My graphics card is a 8800GT and my current OS is Windows Vista SP2.

[rieda1589]

Update your graphics card drivers.

[Mooe94]

I fixed it. For some reason I was using 16bit in Display Settings, I switched to 32bit and Windows Aero appeared again.