My handset (BB9700, purchased <2 weeks ago) is playing with me.

It was perfectly fine for first week, I set up BIS and Google Sync for calendars and contacts. All synced great and I was very happy. Couple days ago I was unable to enter calendar, when I clicked it just didn't open and everything hang. I could switch to other app (by holding BB key or red button) but I was unable to enter calendar. I restarted BB couple times, the same. So I plugged it to my PC, made a backup and wanted to return it but after that it started to work. So I thought "fair enough" and continue using it.

Since then it hangs every approx 20 hours. Power off/restart doesn't help, making backup doesn't help as well. One time I uninstalled MSN client and it started to work again (I tried this trick next time and it didn't), one time I removed and added (couple times) couple entries on google web interface and forced to sync and that "unblocked it". Google sync stopped working today (I think it happened when calendar locked itself). Unfortunately all this methods stopped working and I can't "unlock" BB's calendar (I can see my appointments when I hover on icon on homescreen). I used BB desktop and tried to update software but it displays message "no update required". Menu -> Options -> About displays:
BlackBerry 9700
v5.0.0.421 (Platform 5.1.0.116)
3G Bands 1,2,5,6
Branding version: 1.0.125.697k

I'll appreciate any help as calendar is one of the most important features for me.

I managed to unlock it by removing google sync, installing again, google sync was still failing, plugged off battery for 2 minutes, turned on, calendar still hanging, restarted, uninstalled google sync (it asked if I want to wipe calendar, I said yes), device restarted and I could enter calendar. Not all entries were removed so I went to options -> typed "WIPE" and that wiped calendars. Then I installed google sync and synchronised my calendar, works now.

Question still stays though, is that faulty behaviour or should I just update software or am I doing something wrong (like using Google Sync to sync calendars and contacts and BIS to pick up emails)?