The test SDK regression test:
   com/sun/jdi/SuspendThreadTest.java
crashes when run on 5.0.x on some windows machines(multi core?), but not others.
The test basically just
- sets a bkpt in a trivial debuggee method that is called in a loop
- when the bkpt it hit, the debugger disables it, resumes the debuggee
  and then re-enables the bkpt.
This is repeated 200 times.

On a dual core xeon machine(Windows 2003 Server), the
test always fails before 200 iterations are completed.
On a single processor athlon,(Win XP) the test never crashes, nor has
it been seen to fail on a two processor solx86 machine.

The failure only occurs with the client compiler.
The failure occurs with 5.0_11 and earlier updates (at least those I tried)
back to and including 5.0 FCS.

See the attached hs_err file which came from 5.0_11.
See also:
   4926272: methodOopDesc::method_from_bcp is unsafe
com.sun.jdi.SuspendThreadTest

See, e.g., the tlog file at

http://gtee.sfbay/gtee/results/JDK7/NIGHTLY/VM/latest/JDK6U3/vm/64BITLINUX-AMD64/server/mixed/vm-64BITLINUX-AMD64_server_mixed_JDI_REGRESSION2007-07-15-14-32-29/com/sun/jdi/SuspendThreadTest.jtr

which mentions this bug id.