I've read here and there that there's a known issue with Windows 7, Gigabyte motherboards, certain Intel chipsets, and iTunes. Maybe that's the cuplrit? Just one problem: I have no idea what kind of motherboard or chipset are inside my PC.
Enter CPU-Z, a free utility that reveals all kinds of information about your hardware: processor model, RAM size and speed, BIOS brand and version, and so on. Just the kind of information you might need when trying to troubleshoot a sticky problem like this one.
Of course, CPU-Z can come in handy for more mundane tasks as well, like figuring out what kind of memory to buy when upgrading your system.
A quick check of the Memory tab, for instance, reveals that I have 400MHz, dual channel, DDR2 RAM. And the SPD tab shows me what's in each memory slot. On my system, slots 1 and 2 each have a "1024 MByte" (aka 1GB) Samsung PC2-6400 module. Perfect: Now I know to buy two more just like that to bring my system total to 4GB.
If you ever need detailed information about your PC's inner hardware, CPU-Z can't be beat. And it's a freebie to boot.