Hey I also got the same problem:

I opened the Flyff shortcut at the desktop

It does the patch

I click the Start button

White window and GameGuard splash screen pops up

GameGuard update pops up and disappears

White screen and splash screen disappears

The last thing that disappears is the GameGuard shield icon on the system tray
Please help

This thing irritates me

I just got reformatted my computer and reinstalled Flyff

Any help will be appreciated
PC specs
Processor: Intel Pentium 4 CPU 2.40 GHz
RAM: 480 MB
Graphics card: S3 ProSavage DDR 32.0 MB
OS: Windows XP Professional (5.1.2600) SP2
HDD: C: 20.76 GB (9.54 GB free)
BIOS: Phoenix Technologies 6.00 PG