Okay, been getting this issue a lot myself, as well as am I getting pm's about it.
Solutions:
* Try re-installing Shaiya.
* Uninstall Shaiya, Disk Defragment your Operating System Partition, and the Partition that your have the game installed on.
* Try to Rebuild the Page File (Very similar for Win XP too).
* Re-download the client from a different file mirror and re-install. See Shaiya Download.
* Do a memory test to verify that your RAM is fine. Run it for at least 8 hours or overnight.
Straight from Langerz =))