Blank images with mapscript in redhat enterprise 4

[José Vicente Higon]

Hello,
I have a problem with an application developped with mapscript, I recive 
empty images randomly. Initially, the application was developped in 
windows and it worked fine, when we put it in linux it began to fail 
(readhat enterprise 4 Nahant). Now, we have installed these versions:

httpd-2.0.55
php-5.0.5
postgres-8.0.3
mapserver-4.8.4
gdal-1.3.2
gd-2.0.33
....

I've tried with newer and older versions of mapsrver, gd, php (php4 too) 
, ... but it continues failing. I'm desperate !!
All layers are in debug mode, however when the appplication crashes, the 
output log (error_log apache's) stops be writed and any messages can 
give me any clue.

Can someone help me?

Thanks in advance

-- 

 José Vicente Higón
 Grupo de desarrollo de gvSIG 
 Conselleria de Infraestructuras y Transporte
 Generalitat Valenciana
 Valencia - Spain
 http://www.gvsig.gva.es