Please try using this CVS snapshot:

  http://snaps.php.net/php4-STABLE-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php4-win32-STABLE-latest.zip

Also, you need to give us the exact configure line you have used. (note: we don't support using of the external GD libraries, use the bundled which contains several fixes)

No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
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Same error under debian GNU/Linux_x64 with php 5.2.1:

#0  0x00002ac7ffffffff in ?? ()
#1  0x00002ac71ca19123 in ?? () from /usr/lib/libfreetype.so.6
#2  0x00002ac71ca191e0 in FT_Done_Face () from /usr/lib/libfreetype.so.6
#3  0x00002ac71c8cef6d in ?? () from /usr/lib/libgd.so.2
#4  0x00002ac71c8cd65d in gdCacheDelete () from /usr/lib/libgd.so.2
#5  0x00002ac71c8cf5a6 in gdFontCacheShutdown () from /usr/lib/libgd.so.2
#6  0x00002ac71c0115c9 in zm_deactivate_gd (type=16158400, module_number=16224416, tsrm_ls=0x1522e20) at ext/gd/gd.c:1303
#7  0x00002ac71c23d4cf in module_registry_cleanup (module=<value optimized out>, tsrm_ls=0x1522e20) at Zend/zend_API.c:1945
#8  0x00002ac71c246b58 in zend_hash_apply (ht=0x2ac71c7abec0, apply_func=0x2ac71c23d4b0 <module_registry_cleanup>, tsrm_ls=0xd8ca40)
    at Zend/zend_hash.c:673
#9  0x00002ac71c23b0b0 in zend_deactivate_modules (tsrm_ls=0xd8ca40) at Zend/zend.c:839
#10 0x00002ac71c1f2495 in php_request_shutdown (dummy=<value optimized out>) at main/main.c:1293

Please try using this CVS snapshot:

  http://snaps.php.net/php5.2-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php5.2-win32-latest.zip

"Same error under debian GNU/Linux_x64 with php 5.2.1:"

Please try using the last 5.2 snapshot and RC. If you still have this problem:

Do you compile php yourself?
Which GD do you use? Bundled or external?
Do you have a script?

Please note that we do not support debian package but only install done from the official sources (that's true for the external libgd too, debian's libgd being everything but clean).

It still crashes.  I compiled libgd 2.0.34 and php from http://snaps.php.net/php5.2-latest.tar.gz by myself using the --enable-maintainer-zts configure flag.
The error happens on every page when the gd is accessed by two threads (probably this is the reason the crash happens in different places); when I access only one image it works well.

This example is enough to cause the crash:
http://it.php.net/manual/en/ref.image.php#60410

#0  0x00002b4117be2450 in TT_RunIns () from /usr/lib/libfreetype.so.6
#1  0x00002b4117bdb3af in ?? () from /usr/lib/libfreetype.so.6
#2  0x00002b4117bd1979 in FT_New_Size () from /usr/lib/libfreetype.so.6
#3  0x00002b4117984c58 in gdImageStringFTEx (im=0xf7e7a0, brect=0x438012d0, fg=2, fontlist=<value optimized out>, ptsize=8, angle=-0.26179938779914941, 
    x=0, y=54, string=0xdced58 "80", strex=0x0) at gdft.c:976
#4  0x00002b4117984f8b in gdImageStringFT (im=0x41, brect=0x41, fg=62, fontlist=0x3f <Address 0x3f out of bounds>, ptsize=512, angle=63302.914951680381, 
    x=0, y=0, string=0xdced58 "80") at gdft.c:811
#5  0x00002b41170be6d9 in php_imagettftext_common (ht=<value optimized out>, return_value=0xdced08, return_value_ptr=<value optimized out>, 
    this_ptr=<value optimized out>, return_value_used=<value optimized out>, tsrm_ls=0xd9ae40, mode=0, extended=0)
    at /opt/php5.2-200704300630/ext/gd/gd.c:4260
#6  0x00002b41170be768 in zif_imagettftext (ht=65, return_value=0x41, return_value_ptr=0x3e, this_ptr=0x3f, return_value_used=0, tsrm_ls=0x0)
    at /opt/php5.2-200704300630/ext/gd/gd.c:4164
#7  0x00002b41173232fc in zend_do_fcall_common_helper_SPEC (execute_data=0x43802950, tsrm_ls=0xd9ae40)
    at /opt/php5.2-200704300630/Zend/zend_vm_execute.h:200
#8  0x00002b411731098f in execute (op_array=0xc9eed0, tsrm_ls=0xd9ae40) at /opt/php5.2-200704300630/Zend/zend_vm_execute.h:92
#9  0x00002b4117322cf7 in zend_do_fcall_common_helper_SPEC (execute_data=0x43802e00, tsrm_ls=0xd9ae40)
    at /opt/php5.2-200704300630/Zend/zend_vm_execute.h:234
#10 0x00002b411731098f in execute (op_array=0xdcbef8, tsrm_ls=0xd9ae40) at /opt/php5.2-200704300630/Zend/zend_vm_execute.h:92
#11 0x00002b41172ee13a in zend_execute_scripts (type=8, tsrm_ls=0xd9ae40, retval=0x3e, file_count=3) at /opt/php5.2-200704300630/Zend/zend.c:1134
#12 0x00002b41172a329b in php_execute_script (primary_file=0x43805350, tsrm_ls=0xd9ae40) at /opt/php5.2-200704300630/main/main.c:1794

"It still crashes.  I compiled libgd 2.0.34 and php from
http://snaps.php.net/php5.2-latest.tar.gz by myself using the
--enable-maintainer-zts configure flag."

Please use the bundled library. It contains more fixes and features. It also has a better thread support. To compile php using the bundled version, do:

"./configure" "--with-gd" ... instead of "--with-gd=/opt/"

It is clearly one of the thread safety fixed in 5.2.1 and 5.2.2 and only available in the bundled library. GD 2.1.0 will have them, but that does not change the golden rule: always use the bundled library :)

Cannot be fixed in php, it is not a php bug per se > bogus.