Recently My freind's system simply switched into the Vista Basic Mode without any details, though there is nothing wrong with Basic still Aero is far more flashier and he likes it a lot, I was asked to fix this up, Though I did all the obvious things i shouldm it was not working, I searched net but with no avail, then I came across a siteĀ CleverCretin's Ultimate Step-by-Step Guide to Troubleshooting Windows Aero. (http://clevercretin.com/vista/)

This really helped me out, If you are facing problems check this out, its simple enough