There's nothing on the server side of interest that would help diagnose your problem, so we're going to need to play a little question and answer.
* Are there any tasks on those computers which are suspended, either because the tasks themselves are suspended, or their projects are suspended?
* Is either computer attached to any other project besides PrimeGrid, and, if so, running any tasks?.
* What do your BOINC logs say? Is your computer requesting CPU work from PrimeGrid? Providing the portion of the log that show what happens when you hit the update button may be helpful.
* Are you using app_info.xml and/or app_config.xml for PrimeGrid? If so, please provide the entire contents of those files. I'll also need to see the contents of cc_config.xml from your main BOINC data directory. The last person with a problem similar to yours had something in cc_config.xml that was causing problems, but was not at all obvious.
(Edited to include request for cc_config.xml contents.)
My lucky number is 75898524288+1
(I am NOT an administrator anymore, so please don't PM me with questions. I can't help.)