This may result from an X server bug. This bug appears to be limited to X servers that support `true color' (typically 24- or 32-bit) displays, when using overlay graphics. Restart WAVE, adding the `-S' option to the end of the `wave' command.
This problem may also occur on 8-bit `pseudo-color' displays, if another application such as Netscape has already allocated most of the color map. To avoid this problem, start WAVE before starting Netscape.