Game wont launch
Hi Klipso, in short, no you do not need to do a complete fresh install, GW2 will patch itself. Dunno how tech-savvy you are, try running the client with the “-diag” command line parameter (more explanation here) might help highlight some issue. It might just have been the update server(s) were getting heavily accessed at the time (big update, lots of clients etc), maybe just trying again now might work. Failing all that, might help tech support, if you can, post some details on your system (version of operating system, using 32- or 64-bit client, when did you last do a windows update, that sort of thing).
Gryphons Without Wings [GWW], Australian/New Zealand guild, PvE/WvW (IoJ&SoS), Est. 2008