Phones are like mini computers nowadays.
Every now and then files get corrupted and sometimes the only way to clean out the corrupted files is to do a master reset.
You should back up your contacts before doing so. Else it will be a PITA.
On WinMo phones you can use something like PIM Backup (free app) to do this.
Not sure what is available for your phone.
Basically, I think you can't avoid the master reset 
Good luck.
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