Frequent failure to shut down or restart

Hi,

I've got a pretty new MacBook Pro. It's the current top-of-the-range 17" model (though I expect to be annoyed when Apple issues an upgraded version soon!). 2.6GHz processor, 250GB hard drive, high density screen (1920x1200). It arrived in late November 2007, so it's pretty new.

I love it, and it works really well. However, I have one annoying, intermittent problem that I haven't been able to solve. Sometimes, the machine refuses to shut down properly; and this behaviour also affects restarts.

What happens is that it goes through the normal logging-out processes, to the point when the only thing remaining is the desktop background picture with the twirling 'clock' bars, horizontally centred and about a third of the way up the screen. Normally this twirling indicator appears for a second or two before the machine shuts itself down (and restarts if that's what I've chosen to do). However, if the problem strikes, the machine just sits there with the twirling indicator going around forever.

My only solution when this happens is to hold down the power button to force it to shut down. I try to listen and be sure that the disk is no longer being accessed when I do this, to minimise the chance of corruption, and when I restart afterwards I check the disk with Disk Utility (so far it's always been OK). But obviously I don't like having to do this.

I have no peripherals attached to the laptop: just the power and ethernet cables (usually; I only use it away from the desk infrequently). The only external peripheral I use with this machine is a Bluetooth mouse. I do have a .Mac account, if that's significant.

The problem has been there from an early stage. I do have various applications installed that run at log-in, but nothing that I'd consider 'dangerous', or that aren't well tested. E.g. I have SnapzPro X installed, but that's a popular product and I can't imagine that it'd be the cause of what's probably a rare problem. Besides, virtually everything that's installed on my MacBook Pro is also installed on my desktop G5, where I've never seen this problem. I don't have anything installed that modifies the system (haxies and their ilk).

Also, I first saw this problem when the machine was only two or three days old and I'd barely installed any software on it. So I'm reasonably sure that it's not related to third party software. Yet I don't see how it can be a hardware problem either, given that it only happens sometimes. Yesterday, for example, after installing the latest QuickTime 7.4.1 update, my machine installed the update and restarted itself correctly. Then I noticed an odd problem with my keyboard LEDs (Caps Lock and Num Lock: they were both on when they should be off) so I restarted... and I got the problem again. And I'd done virtually nothing after the previous reboot, beyond running TextEdit.

Very strange. I hope that it's an obscure Leopard problem that Apple will fix with the forthcoming 10.5.2 update (this MBP came with Leopard pre-installed), as I really don't want to find out that my laptop is actually faulty. I just wondered whether anyone else had had similar problems and maybe got to the bottom of them.

The most unusual thing about my MBP is that I opted for the faster processor (2.6GHz). Could this possibly be a factor? (I wouldn't have thought so myself, but you never know.)