Hmm, I don't really see a bug, neither in Kernel 3.10 nor in Virtulbox 4.3.2. I mean, I haven't experienced any problem, even after last upgrade of Kernel and / or Virtualbox.
But, I'm using KDE 4.11 (64bit) with Kernel 3.11 (not 3.10) in combination with Virtualbox.4.2.18 before and now 4.3.2.
Maybe there is a problem with Kernel 3.10 in some combination with Virtualbox, but as I've said, I haven't experienced any problem.
Just an idea: Could you consider to install Kernel 3.11?
-Linuxfluesterer (I love KDE ...)
TTIP is NOT YET stopped. Especially consider NHS and ISDS topics. Talk to your local politician to open eyes for danger to democracy because of TTIP