What does "can't find linker symbol for virtual table" mean?

[Geoff Alexander]

Can someone tell me what the following message means:

  (gdb) print name.c_str()
  can't find linker symbol for virtual table for `FileCollection' value

The FileCollection collection class was compiled with -g using g++ 2.95.3 on
SuSE Linux/ix86 7.3.  I am running gdb 5.2 also on SuSE Linux/x86 7.3.

Thanks,
Geoff Alexander