I get this all the time on Holodeck. Most of the time happens when beaming from SFA up to ESD. Think it started happening when they increased the instance cap to 75. Same with DS9, but hardly go there. Be good when SB is finished and has everything.
This happens to me on Holodeck all the time. Seems to only happen when entering or leaving DS9, ESD, and Memory Alpha space and ground maps. I assume there's some sort of cap to the maps and either I'm getting stuck in a queue or tossed to the side. A reload seems to work 80% of the time.
Rarely if ever happens to me on Holodeck, but just spent 20 minutes staring at a Tribble ESD loading screen with little progress until apparently alt-tabbing got to be too much for it, and it crashed to CrypticError.
Not sure if it's Tribble, or the fact that I hurt serverhampster's feelings by downloading the SWTOR client in the background.