programs not behaving the same on each invocation sounds a bit like hardware issues, not software problems.
I'm using xpdf quite a lot on my AMD64 without any problems.
Also, if you can try to get a backtrace from xpdf without TLS enabled, it would help:
LD_ASSUME_KERNEL=2.4.1 gdb xpdf.bin
programs not behaving the same on each invocation sounds a bit like hardware
issues, not software problems.
I'm using xpdf quite a lot on my AMD64 without any problems.
Also, if you can try to get a backtrace from xpdf without TLS enabled, it would help:
LD_ASSUME_ KERNEL= 2.4.1 gdb xpdf.bin