i found the problem!!!!
FTB it's in conflict with Cauldron stats control (another free .Net control) in web.config.
Infact, deleting this line from <system.web> tag everythink is ok:
<httpModules>
<add
type="CauldronStats.Analyser.CauldronStatsModule, CauldronStats"
name="CauldronStats" />
</httpModules>-->
Can you correct this bug???
i hope!!
bye bye
Andrea