I got through the error with the Try...endTry set of instructions :

	Try 
		If !Used('clienti')
			Use clienti Again In 0
		EndIf 
	Catch to oErr
		If oErr.errorno = 9
			If !Used('clienti')
				Use clienti Again In 0
			EndIf 
					
		EndIf 
	Finally 
		If Empty(Sys(14,1,'clienti'))
			Select 'clienti'
			Set Index To 'clienti1'
		EndIf 	
	EndTry 	

Now it goes on without errors but I don't like this solution very much...