Exact same problem here. Using XP at my office, Windows 7 at home. All was fine with version 5. Upgraded version 6 and now get errors on my home system. I believe the red X error was: "Experienced an unexpected error". Here's what I've done so far:
Did the basics such as pulled the battery to let the Storm re-boot. I deleted all calendar and contact entries from Storm using DM to make sure the entries match between Storm and PC at work. Then come home and get errors on that PC.
Uninstalled 6 at home, loaded 5, now 5 doesn't work either.
Deleted calendar and contact data from Storm at work then synced
Created a separate PST file with only contacts and calendar from work Outlook file. Added that file to my home Outlook and used that file at home to replace all calendar and contact entries at home so that the Storm would/should have exactly what is in my PC Outlook files.
It reads all the entries on the Storm then on PC, then crashes with "Unknown Error Reported"
Another annoying thing is that my calendar entries seem to always get confused since my e-mail address at work is different from my e-mail address at home. My name shows up for the meetings with a conflict because during the sync, it sees my personal e-mail address as the attendee on my home PC but it sees my work e-mail address as theh attendee on the work PC. DM 6 seems to be confused with this issue. It's always been there but DM 5 somehow resolved the difference.
Hope this helps others to get a solution. I'm not an expert and have found this forum and am hoping that the real experts will have suggestions.