Unhelpful error message "Can't open module"

[jeffythedragonslayer]

When I try to open some files I get this msgbox:

but it doesn't tell me why.

[jeffythedragonslayer]

A look an TFormMain::ModuleOpen in UnitMain.cpp reveals that this error is displayed when:

• fopen returns 0, or
• gss_find_tag returns a value less than zero