If you experience long Windows NT startups or have problems with shares (viewing, creating, mapping) or other logon problems, you may have messed up the default permissions on the LanmanServer registry keys.
The default permissions on this key (and it's sub-keys) should be:
Administrators Full Control
System Full Control
Everyone Special Access
To set these permissions, use the Windows NT Registry Editor, REGEDT32.EXE, and select:
From the Security menu, click Permissions. When you select Special Access for Everyone, you may need to double click the Everyone Special Access line to get the Special Access sub menu.
Don't forget to check the Replace Permission on Existing Subkeys box.
You may wish to see Tip 162 for additional Flaky logon problems.