According to the post above (thanks kratos3946) this seems to be an Eclipse CDT bug. You can try to revert CDT to an older release, and keep us informed on the result. There was a release on December 20, just before you got this problem, so reverting to the previous release may be enough.
I agree this is disturbing but we are not responsible of bugs introduced by Eclipse and cannot test all Eclipse releases, in all configurations and on OSes. Right, Eclipse is cross-platform Java code, but both GUI toolkit’s and system interface (like network) are platform dependent, and your problem obviously fall into this category... That’s why we need information like OS, OS version, Java version, Éclipse version, etc.
Hope this will help,