Try deleting the file sitting in the workarea.

Eg: C:\\users\\[yourlogonname]\\documents\\Micro Focus\\Net Express 5.1\\Workarea\\nxdebug~ds

I never remember which one of two solutions works.

The other is to rename the HKEY_CURRENT_USER\\SOFTWARE\\Micro Focus\\NetExpress registry key, but you'd have to setup all your preferences again etc.

The onus is on you to take a backup :)

Neil