Crashing VirtualBox - host=W7/64bit, guest=WinXP

[DerellLicht]

I'm running VB V4.3.4, host is Win7 64bit, guest is Win XP SP2. This system has been running fine for months.
Now, I'm trying to install the SP3 service pack on my guest OS, but it gets about 10 minutes into the upgrade procedure, and then VirtualBox itself crashes!!
I have performed this SP2-SP3 upgrade successfully on other XP guests in the past (on other computers, of course) with no problem;
Does anyone have any idea why I am having this problem now?

[noteirak]

Please provide the VM log file as a zip attachement.

[DerellLicht]

Dang, too late... I tried updating to SP3 via a different method, and killed the installation entirely. Oh well, re-install time. This time I'll upgrade to SP3 before I install any other software.