Guild Wars 2

It was working fine then tried to play today and as soon as i click gw2 ico i get a message saying: “A serious error has occurred that prevents the program from continuing to run”
i click show details and i get this.

—> Crash <—
Assertion: pngPixelFormat == GR_FORMAT_ARGB_8888
File: ..\..\..\Game\Launcher\Windows\Launcher.cpp(2871)
App: Gw2.exe
Pid: 3088
Cmdline:
BaseAddr: 00400000
ProgramId: 101
Build: 15926
When: 2012-11-07T14:56:24Z
Uptime: 0 days 0:00:00
Flags: 0

—> System <—
Name: COMPUTER_1
IpAddr: 192.168.1.78
Processors: 2 [AuthenticAMD:15:11:1]
OSVersion: Windows 4.0 (32 bit)

—> System Memory <—
Physical: 2303MB/ 3454MB 66%
Paged: 3222MB/ 5337MB 60%
Virtual: 1159MB/ 2047MB 56%
Load: 33%
CommitTotal: 2115MB
CommitLimit: 5337MB
CommitPeak: 2729MB
SystemCache: 1835MB
HandleCount: 31318
ProcessCount: 49
ThreadCount: 712

—> Process Memory <—
Private: 823MB
WorkingSet: 18MB
PeakWorkingSet: 18MB
PageFaults: 4751

—> Game Context <—
MapId: 0
Flags: 0×241
ElapsedTime: 00:00:00

—> World State <—
<WorldState />

[DbgHelp.dll is C:\WINDOWS\system32\dbghelp.dll]
[DbgHelp.dll version 5.1.2600.5512 (64/32-bit compatible)]

—> ClientContextThreadProc Thread 0xae8 <—

A load of code here
and then

—> Error Logs <—
Image is corrupt: Unknown image file format.