ICal keeps crashing at startup

Question

Hey I've been reading a bunch of the discussions, but I have yet found a solution as to why my iCal keeps crashing. I've reinstalled the system and installed the HelveticaNeueu.dfont. Now I did create a new account and iCal does work on that account. Here is a copy of the log I get when iCal crashes. Thanks everyone in advance for any help.
===== Monday, June 18, 2007 10:04:55 AM US/Pacific =====
2007-06-18 10:05:06.110 iCal[650] Invalid char _ for PropertyName in line 42
2007-06-18 10:05:06.232 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.250 iCal[650] Invalid char _ for PropertyName in line 54
2007-06-18 10:05:06.273 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.285 iCal[650] Invalid char _ for PropertyName in line 49
2007-06-18 10:05:06.308 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.317 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.326 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.335 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.344 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.351 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.358 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.365 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.371 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.377 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.383 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.393 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.402 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.409 iCal[650] Invalid char _ for PropertyName in line 39
2007-06-18 10:05:06.415 iCal[650] Invalid char _ for PropertyName in line 38
2007-06-18 10:05:06.422 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.427 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.432 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.437 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.442 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.447 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.454 iCal[650] Invalid char _ for PropertyName in line 48
2007-06-18 10:05:06.473 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.479 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.485 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.494 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.507 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.517 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.524 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.530 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.537 iCal[650] Invalid char _ for PropertyName in line 49
2007-06-18 10:05:06.559 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.565 iCal[650] Invalid char _ for PropertyName in line 41
2007-06-18 10:05:06.570 iCal[650] Invalid char _ for PropertyName in line 39
2007-06-18 10:05:06.574 iCal[650] Invalid char _ for PropertyName in line 36
2007-06-18 10:05:06.580 iCal[650] Invalid char _ for PropertyName in line 52
2007-06-18 10:05:06.602 iCal[650] Unable to save invitation items
2007-06-18 10:05:06.606 iCal[650] Invalid char _ for PropertyName in line 38
2007-06-18 10:05:06.613 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.619 iCal[650] Invalid char _ for PropertyName in line 37
2007-06-18 10:05:06.624 iCal[650] Invalid char _ for PropertyName in line 43
2007-06-18 10:05:06.626 iCal[650] * -[NSCFString longValue]: selector not recognized [self = 0x152f9e00]
2007-06-18 10:05:06.626 iCal[650] An uncaught exception was raised
2007-06-18 10:05:06.626 iCal[650] * -[NSCFString longValue]: selector not recognized [self = 0x152f9e00]
2007-06-18 10:05:06.626 iCal[650] * Uncaught exception: <NSInvalidArgumentException> * -[NSCFString longValue]: selector not recognized [self = 0x152f9e00]

Answer 1

careful with that axe eugene.
Here's the safer way to reset Sync Services:
1. Turn OFF all sync services in Entourage preferences 

2. Quit ALL Office applications (including Daemon)

3. Quit Safari, Address Book & iCal and all applications synching through 
.Mac (Transmit, Yojimbo...) 

4. Use Activity Monitor to quit SyncServices
Only then:

5. Delete the contents of ~/Library/Application Support/SyncServices/ 
Optionally: if you want to replace all data in the system Address book and 
iCal with Entourage data, delete all iCal & Address Book Data Files: 
~/Application Support/iCal/* 
~/Application Support/AddressBook/* 
~/Library/Caches/com.apple.iCal/* 
~/Library/Caches/com.apple.AddressBook/* 

7. Open the .Mac System preferences and make sure .Mac synching is enabled

8. Restart all applications that sync to .Mac (Safari, Address Book, iCal, 
etc.... and Entourage).

9. Turn ON Sync Services in Entourage preferences.