This has been an intermittent problem for twenty years, with many different operating systems. The OSs fix their print spoolers, swap disk algorithms, etc, but then we just print bigger files 'til we break it again. More RAM will probably help, but I think you said you'd need a new computer to put more RAM in. In the meantime, I suggest you lower the resolution of the files you're sending to the print driver. Halving the pixels/inch will usually make the spool file a quarter the size (but not always -- it depends on the print driver).
It happens on big machines, too. A few months ago, a print job consisting of one 40x60 print hung on a 48GB machine. I found out that I'd left the LR resampling at 720 ppi from a previous job, Setting it to 360 fixed things.