Certain conditions can cause SourceForge Explorer to stop functioning properly and to start behaving oddly. This can manifest itself as the app not logging you into SourceForge, or forgetting your settings, or other general strange behavior.
To correct this behavior, you can delete your stored profile from within SourceForge Explorer.
If deleting the profile doesn't correct the behavior, try deleting the profile again, then uninstall and reinstall SourceForge Explorer.
If that still doesn't fix it, delete the profile, uninstall SourceForge Explorer, and delete the registry key HKEY_CURRENT_USERSoftwareVA ?SoftwareSourceForge ?ExplorerWindowsMainWindow (and all subkeys). Then reboot, then reinstall SourceForge Explorer.