viewport problem - see nothing in top view

[max.m]

hi there, i face a strange problem. i work on an interior scene. for hours everything works fine, suddenly i see nothing more in the top and the bottom view. zoom extends, scolling and zooming in and out brings no solution. i even see no grid(also when i uncheck it and check it again). also tried to model a box in the top view, i only see the lettes of the axes of coordinates of the new object - and nothing else. when i change to any other view (than top or bottom)in the viewport everything is ok.

Edited April 27, 2009 by max.m