IIS6 Anoymen zugriff

Hello,
I have three servers that are member servers in a trusted domain.
One has IIS 6.0 on 2003 and the other IIS 5.0 on 2000.
And one SQL2000 on 2000.
Connection (with PHP5) to SQL server from IIS6 with Anonymous Access
( IUSR_myserver ) doesn't work, from IIS5 work!

Any suggestions?