I have the same issue occasionally, what usually helps is rebooting everything (including the router and cable modem) and reloading EQ.

For me, it seems to happen mostly when I've had EQ logged on for a few days. You can also try doing a complete file check from the EQ loading screen, as the files sometimes get corrupted. Also try updating your video card drivers.

Has this always happened since you started using the computer, or did it work well at one time?

Also bear in mind that with the new expansion and multiple emergency fixes they've done lately, things may be running less than perfectly on the server end.