Win2K and NT4 have security, whereas 98 does not. This is why the Net Time setting in your logon script is not working in Win2K. Your NT domain account running on Win2K needs the right "Change the System Time". A default user does NOT have the right. Therefore, in the NT/2K world, a normal user cannot change their computer's clock. This also applies to logon scripts. They run under the security context of the user logon account that the script is doing stuff for. So, when the logon script issues the Net Time command, the rights of the user account are checked and revealed to not have the right. Due to this, the time sync fails.
So, go into User Manager for Domains on your NT PDC. Click Audit -> User Rights. In the dropdown, select Change the System Time. Click Add and andd your account.
Not being able to change the clock is a security issue, technically, but I have always thought it was just a big pain!
As for mapping the drive to J:\users, Win2K support drive mapping to subfolders, instead of just mapping to the share. So, where in NT and 98 you can only map to \\SERVERNAME\SHARENAME, in Win2K, it can handle \\SERVERNAME\SHARENAME\FOLDER. Check out your logon script, and make sure it it not mapping too deep.
Hope this helps.