gdb continues unexpected

[Dirk Zabel]

Hi,
I am using gdb 6.7.1 on a ppc embedded target (debugger and debuggee are
both running on the target as there are enough resources). The kernel is
2.6.21. Now sometimes I encounter the following misbehaviour: if I want
to single step (command step) or step over a function call (command
next), the debugger seems to execute the "cont" command instead, i.e.
the program continues until I press Ctrl-C or it stops on another
breakpoint. If it matters: the debuggee uses threads. If I start
debugging, the welcome message says:
GNU gdb 6.7.1
Copyright (C) 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "powerpc-603e-linux"...
Using host libthread_db library "/lib/libthread_db.so.1".
Breakpoint 1 at 0x1003383c: file cm_assert.c, line 26.
(gdb)
[the breakpoint shown is ok, it's defined in my .gdbinit file]
This happens not always, but of course every time I need the single step
mode badly. (Some AI built into gdb to needle the programmer? :-)

If I use stepi to step by machine instruction, the same happens. The
unwanted continue happens on different addresses, btw.

Any suggestions?

Regards,
  Dirk