Old ITfag here.

Re: garbage collect. I spent my formative years programming commodore 64s in old basic. There was a routine that the machine used to run on a regular basis known as 'garbage collect'. The area of memory used for temporary storage of data would get too big and have to be cleaned up. I assume that modern operating systems work on a similar basis, the difference being that with 24/7 operations you can't just switch stuff off. Garbage will be all the stuff written to temporary working files, in memory and on disk. Sloppy coding, or more to the point really old darpa coding might have left telltale crap hanging around for years.

Might just explain the fb outage, as they desperately reboot systems to clear down incriminating evidence.