The explanation is here:
So, apparently, the grid wrongly returns 0 as the maximum number of groups on login !... I'll have to add a check for such a silly case, but it should not be happening at all: the grid is obviously misconfigured !
I also notice that you got crashes (CoolVLViewer.dmp files): this should not happen ! Please file a bug report for the cases that make the viewer crash (the crash is unrelated to the group issue, so please, open another topic for it).
Your network, or your network route to the grid, or the grid services themselves also seems quite flaky, with a lot of out-of-order UDP packets reported in the log, as well as 404 errors for assets that should exist, and invalid responses from sim server. If I were you, I'd check with the grid admins to see what's going wrong on their side...