I have, very rarely, had it happen while doing nothing. Most notably, I recall it happening in Plane of Storms. We'd be doing nothing more than zoning everyone in to start getting ready for BoT keys. However, I can't attest that there was nothing going on at the time. Someone may have been buffing and possibly glitched everyone else as well?
However, this same behavior occurs if your connection should drop for, say, fifteen seconds or so while doing either something or nothing. Our router at work was acting up for about a week, where it would do exactly that. (I knew it was connection related because we host a Ventrilo server on the server box as well, and we would all lose that connection as well.)
The lag bar would consistently go out to about 83%, then jog back up to 100% in the midst of whatever we were doing. Some people would recover, some wouldn't. Those who didn't would have the behavior described above. The server sure does its best job to jog you back up to where the server is, but it doesn't always take.
|