There is a bug report regarding files greater that 2Gb on the perl5_porter's mailing list. Apparently it applies to most 64bit systems that have large file support (and that includes Solaris 2.6). You can
for yourself.
I would imagine that a likely solution would be to work with perl above 5.004_04, but you already stated that you're working with 5.005_03, so I really don't know what to gather from this.