Guild Wars 2

I can’t enter Applied Development lab instance in Rata Sum to continue Asura quest. The quest name is “Field Test”. Everytime I try to enter the instance, the loading takes as long as 4 minutes, and then I get an error message saying the game has lost its connection to the server.
I try other instances in Rata Sum and they work fine. So I don’t know what happens.
Below is my comp specs:
OS: Windows 7 Professional 64-bit.
Processor: Intel Core Ivy Bridge i5-3570K CPU @ 3.40GHz
Memory: Gskill Sniper DDR3 1600 8GB RAM
Motherboard: ASRock P67 Extreme4 Gen3.
Graphic card: EVGA GTX 570 HD 2560 MB.
Hard drive : Crucial M4 SSD 128 GB and WD 1TB 7200 RPM
I’ve attached NetworkDiag in case you need it.
Please help.