crazygazza,
You need to ditch 4.03 because even though it has a setting for 160x120 it actually converts to 176x128 which is why your player is crashing.
If you need to move all traces of 3.68 so you can install 3.57 you need to open regedit and got to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Curr entVersion\Uninstall. You will find a series of subfolders with alpha numeric names like this {7784A172-61F1-445E-8368-601607E0DD22} click on each one until you find the entry related to MP3 Player Utilities 3.68 displayed in the right panel, then delete this folder. Then do the same here HKEY_CURRENT_USER\Software\Microsoft\Installer\Pro ducts\
You should now be able to install a new version.
To use 3.57 to convert to 160x120 you need to manually edit the transform.ini as outlined in this post
HERE