I have a pc running running boinc. It"s a pc I bought this barely usable thing when my last one died and it kept me alive until I could get the parts for a respectable unit running again. Yada yada .. The only thing this 'challenged' pc does is boinc. Windoze 8

Problem.. Milky Way job (ready to start) doesn't run. all other jobs have have finished. When I allow new tasks, they complete.
If I abort, It could happen again??? It's an ps_nbody job. CPU always, GPU always. Reboot doesn't help.

Do I abort, swallow my first error and move on?

Milkyway nbody jobs (both ps_nbody and de_nbody) are usually issued as MT - multi-threaded - jobs. They are set - at download time - to use every CPU core available to BOINC *at that time*.

If you subsequently change your preferences and reduce the number of CPU cores available to BOINC, the local client won't be able to schedule the task - it'll never find enough spare resources. If you've done that, you might be able to shift the task by temporarily going back to allowing BOINC to use 100% of everything - but then you'd risk the same thing happening with the next task you are allocated.

Unless you really enjoy the thrill of the chase, I think it would be best to abort the task. Subsequent tasks issued with your current preferences in place should run with those preferences.