Java HotSpot Virtual Machine

I have a natural language processing application that runs fine with the 32-bit jvm (on a WINTEL machine), but failes using the 64-bit jvm (on a SuSE 9.3 with AMD64).

#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
# SIGSEGV (0xb) at pc=0x00002aaaaa5830fd, pid=8429, tid=1076607328
#
# Java VM: Java HotSpot(TM) 64-Bit Server VM (1.5.0_05-b05 mixed mode)
# Problematic frame:
# C 0x00002aaaaa5830fd
#

In the application, I place objects (they basically contain a String) in a Hashtable that have overwritten the hashCode() and equals() methods. There are cases where objects share the same hash value (in my case when objects contain two identical words except for differences in capitalization). I have read that this is valid as a hash bucket can contain more than 1 object. Also, in my application, the equals() method does not enforce a match to a single object. Most often, I do lookups in a case-sensitive fashion, but when I do a case-insensitive lookup, for example "java" would would equal "jaVa" and "javA" in in the hashtable.

Could it be the cause of my troubles in 64-bit java?
thanks,
Dan