Windows stability?

So I’m trying to rename a folder on my mom’s computer, and Windows keeps telling me it can’t, because access is denied, because "the file is in use."  Which means that some other program left some hook unreleased after it closed, which is annoying.  I open up the task manager and exit all the miscellaneous stuff that isn’t a background process, and I still can’t rename it.  Sometimes Windows is just dumb like that, and I know from experience that rebooting the PC will make it work.

But as I’ve got the process manager open, I notice that "System Idle Process" has accumulated some ridiculously large number of HOURS of processor time.  I run net statistics server and learn that this system has been up since May 15th.  MAY FIFTEENTH!!  That’s over 20 days!  I don’t know what my mom and brother are doing... or NOT doing... on this machine, but that is way longer than I can manage to keep my Windows boxen running without a reboot.  Granted, I have some as-yet-unresolved problem that causes random lockups, but.... well, but nothing, that is the point... Windows machines don’t stay up that long.

Well, apparently some of ’em do.