If you use a Windows Operating System:
Please use "Process Explorer v16.05"
By Mark Russinovich - a tree-type Utility w3hich can show you what is happening behind the scenery - You can Stop Process, Pause Process (Right click on a Process and see the various Options.
There are no "Bugs or Malware" in "Process Explorer, ensuure you get it from the above link only, as some D/L sites add unwanted "extras".
Get the free Utility from:
https://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
Run that, and you will probably find, like I did, that your RAM is almost all used up, the CPU soldiers on, but gets nowhere.
When I built this PC, I installed 32GB of RAM, on the basis that I would never use all that RAM, so processes would never stall.
However, recently I had freezes in BOINC projects, and could not do other work either (My PC runs 24/7)
Problem was "memory-stealing" applications, which gradually used all the RAM.
In "Process Explorer" click on the "Physical Memory" graph, the pane opens and you can see exactly detailed RAM usage, plus other variables.
Now to get over the problem, I now sometimes clean out all Cache, .tmp files etc, and then Re-boot twice daily.
Advise your progress, you may have to stop BOINC and Re-boot to read this.
Cheers
Kerry