xmarks for safari on mac version 1.2.0 can't sync (canceled), new bookmarks duplicated many times

i use xmarks 1.2.0 with safari 4.0 on mac os 10.5.7. it works fine before. the problem started a few days ago probably after the last update (of safari or xmarks or both). now every time it sync, no matter automatically or manually, it ends up with a question mark on the icon and a 'sync canceled' message on the control panel. when i check my bookmarks on safari after the 'canceled' sync, i found out that all my newly added bookmarks has been duplicated at least dozens of times. if there are old bookmarks in the same folder, sometimes they mix together. i have to delete them one by one, it happens every time and it's really frustrating.

i also tried manually upload the bookmarks to server, it went ok till "uploading local changes to server", then after a minute "sync failed unexpectedly, please see log file." and "Operation could not be completed. (Unable to perform upload calculate/upload error 0.)" when i try to check the log file, it either won't open, or crash my textedit.

anyone has any ideas of what's going on?

(i use xmarks to sync between safari and firefox on mac, and firefox and ie on windows. all the other three works fine.)