Sometimes, I have similar problems, however, my case is different. I sync with Lotus Notes (including calendar) at the office and with MS Outlook at home. Therefore, sometimes I have problems with syncing - unresolved items and/or sometimes system hang-ups. However, it does not make me hard-reset. I expect that this is some kind of competibility of Lotus and Outlook.
As for your case, did you create any unusual items inside the calandar? Added attachments, pictures or similar? Maybe, it caused the problem?
As for support cases on HP site, they do not work at least for more than a month. I tried it several times, but had the same results
