JRE 6 Update 6 crashes intermittently in ZIP_GetNextEntry(), newEntry() resp.

The pattern is homogeneous and looks like:

Stack: [0xfe48f000,0xfe4df000], sp=0xfe4dde04, free space=315k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [libzip.so+0xb256]
C [libzip.so+0xb4a0] ZIP_GetNextEntry+0x3c
C [libzip.so+0x6cf3] Java_java_util_zip_ZipFile_getNextEntry+0x1f
J java.util.zip.ZipFile.getNextEntry(JI)J

(see attached 3 hs_err_pid.log files)