Sometimes my brain stops in group meetings at work, which is the worst, which, actually, is probably why it happens there --the most is on the line; i.e. stress.
I can push through, but it's obvious I am having trouble speaking. It takes a lot of mental preparation and talking myself down to prevent such events. I get really nervous too (anyone else have that).
I don't think my symptoms are quite as sever as the others here, since I can work through it, mostly.