i have a WL-500G not a WL-500Gx.
Wrong Firmware installed. With Firmware restauration Tool the FW for WL-500G installed. Everything works fine now.
http://wl500g.info/showthread.php?t=1329
HP895cxi winXP Asus WL-500G FW1.9.5.0 at LPT and LPR-Server = success