can someone answer me a ?? about XP?

If you're not getting the login screen or fast user switching, it's likely that another program is interfering with this stuff, as all versions of XP have this. One program that I know does this is Symantec PCAnywhere, it replaces msgina.dll with its own version for security reasons. If you have PCAnywhere installed, an uninstall will fix this, and as long as you don't reinstall the host portion of the program, it will remain fixed.

Sounds like you have Novell Netware installed? Are you on a Novell network? Is this box at a work establishment? If so, you're screwed on the log-in screen. If not just unistall the Novell software. Of couse I could be wrong but this is how my work computer is set up.