After seeing this is becoming quite a common thing for Vista users, and after trying to explain this procedure to someone in the Help Room,
I though a short (OK maybe not so short) guide would be helpful.
This should correct errors with not being able to save settings or use the library properly.
Ensure your account type is Administrator
Browse to C:\Program Files Right click your WinMX and select 'Propertys' as shown here
On the WinMX Properties Dialogue Box select 'Edit'
Select 'Find Now' and select YOUR useraccount name from the search results and click 'OK'
Select YOUR useraccount name from the list, and tick the 'allow' box next to 'fulll control' Select 'Apply' and 'OK'
Select the 'Owner' Tab and click on 'Edit'
Select your useraccount name from the list, tick 'Replace Owner on Subcontainers and Objects' Clcik'Apply' and 'OK'
'OK' the following dialogue box
Click 'OK' on all remaining widows.
Once again bring up the propertys for the WinMX Directory
Select the 'Security' tab and click on 'Advanced'
On the 'Permissions' tab select 'Edit'
uncheck 'Include inheritable [ermission from this object's parent'
You will be presented with the following dialogue box, select 'Remove'
'Apply' and 'OK' all remaining windows
if you still encounter problems with saving settings or your library, Close WinMX, delete the setting.dat & lib4.dat files from the winmx directory and allow WinMX to re-create them when re-opened.
Thanks to MicroMecca for this guide and Images.