I have a problem with Mathematica kernels consuming 100% CPU, even when they seemingly idle: I start Mathematica (version 10.1.0 for Linux x86, 64 bit on Linux 2.6.32, server with 4 cores, 16 GB RAM). A process viewer such as "top", however, reports 100% CPU load on the (two) kernels, even before I have issued the first command. The command prompt works fine and is responsive and fast as always, but the kernels remain permanently at 100%, even hours after startup. The same happens on all additional kernels after running ParallelTable or such. Once I quit the frontend, the kernel processes terminate as they should.
I have tried renaming the .Mathematica/Kernel/init.m file and also the Applications/ folder to rule out any faulty initialization on my side. Besides that, have not modified any system folders or files.
top reports a stable memory consumption of VIRT=1051m and RES=71m or similar both for either kernel, so it doesn't look like the Linux kernel is swapping (the server is was idling when I ran the last test, anyway).
It looks like the kernels are constantly trying to do something in parallel to their regular (and fully functional) operation that hangs.