system32 folder opens when logon into windows XP

One possibility, not very likely, is that logon restores your open folder. You can set Windows not to open the folder at logon: Explorer - Tools - Folder Options - View and deselect 'Restore previous folder windows at logon'.

The other possibility is that a shortcut in the startup folder in your profile or the profile of All Users or possibly in the Run key of the registry hives HKLM or HKCU runs "explorer.exe c:\windows\system32". Let us know if you need further instructions how to check these options.

Go into msconfig,startup tab,click on hide all microsoft programs. Something on start up is causing it to open so you'ld have to figure out what program in msconfig is the culprit.Then you can disable it.
Also as previous poster said,editing the registry is an option, allways back it up first though!