Most of the time, my Compaq AMD64 laptop would hang on the blue screen when booting up. It would display "Windows is starting up" and sit there for at least 15 minutes. What I did before was just hold the power button down and try to let it boot again. And sometimes it'd boot up right. Well, I decided to see if there's a better solution than this. It turns out that there's some sort of issue with the DEP
(Data Execution Prevention) and the AMD 64 processor.
Microsoft has some instructions here
on turning of DEP permanently. But, I couldn't run bootcfg. There's a helpful thread here
on the AMD site. Basically, you have to modify the boot.ini to use "/noexecute=alwaysoff /fastdetect". To edit the boot.ini, right click "My Computer" / Properties / Advanced / Startup and Recovery Settings / Edit. To verify that it is disabled, click on Performance Settings / Data Execution Prevention and it should be greyed out.