I've been able to shut down my Windows XP x64 SP2 quite nicely in about 10-15 seconds, but after a "sweet" hardware failure and getting my CPU, motherboard and graphics card replaced and having reinstalled the OS, shutting down takes about 2 minutes. After clicking Turn Off, my computer seemingly does nothing for said amount of minutes and then finally switches to the usual Logging Off -> Turning off windows routine which takes about 15 seconds. During these 2 minutes I can still browse my files and open/use some programs, but it will eventually mention something about rundll.exe? or another system file not being able to run, obviously due to Windows trying to shut down.
My old computer parts: CPU: AMD Athlon X2 6400+ GFX: nVidia GTX8800 Mobo: ASUS M2N
My new/current parts: CPU: AMD Phenom X4 9950 GFX: nVidia GTX260 Mobo: ASUS M4A78 PRO RAM: 4GB DDR2 SDRAM (unchanged)
I have also tried: Defragmenting my drives with Smart Defrag, doing a full malware/virus scan with ESET Smart Security 4.0, without any noticeable improvements.
If needed I will upon request conduct more tests.