This is not so much a bug report, as a follow-up to numerous bug reports submitted by my patcher upon crashing.
GW2.exe kept crashing when it tried to update, and the error report had “semaphore timeout period has expired” in the details.
Turns out the issue isn’t with Guild Wars 2, but that a part of the GW2.dat file (being so huge) was in a part of the HD that had an error of some sort.
(Not an IT professional here, my understanding is rough.)
Using CHKDSK with Administrator privileges and the /f flag fixed whatever the issue was with the HD, and the patch was successful.
Just letting this be known.