Failed sync in IE (possible connection to XMarks for Chrome)

I modified some bookmarks in Chrome, and synced with the xmarks server using the XMarks Chrome extension. This went fine, and my bookmarks show up fine on my.xmarks.com.

I then initiated a sync from IE and received an error notice with the following details:

Unexpected error during synchronization XmarksException [source: internal, id -50]; Conflict: duplicate rids detected on insert tqw7d3: ,bind, bnid:ojonW3

I tried syncing from Firefox, and that went fine.

I attempted a forced download to local from Xmarks for IE, and received a different error notice: Internal error while writing to your Favorites: XmarksException [source: windows, id: 5) couldn't move file. (This is starting to look like a problem with IE.)

I exited XMarks for IE and exited IE itself.

I then restarted XMarks for IE and was able to sync successfully.

Versions:
IE: 8.0.6001.18702
Xmarks for IE: 1.0.11
Chrome: 4.0.206.1
Xmarks for Chrome: 0.4.22