Sync failure

[c.bossola]

I'm used to getting this error message when my desktop tries to sync with Collaboration Suite of my web provider (many time a day):

java.lang.NullPointerException
at com.zimbra.cs.account.offline.DirectorySync.syncSi gnature(DirectorySync.java:374)
at com.zimbra.cs.account.offline.DirectorySync.syncAc count(DirectorySync.java:266)
at com.zimbra.cs.account.offline.DirectorySync.sync(D irectorySync.java:175)
at com.zimbra.cs.account.offline.DirectorySync.syncAl lAccounts(DirectorySync.java:122)
at com.zimbra.cs.account.offline.DirectorySync.access $000(DirectorySync.java:55)
at com.zimbra.cs.account.offline.DirectorySync$1.run( DirectorySync.java:70)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)

Besides, email filters do not work neither on my Desktop nor on the Collaboration Suite. There could be a link with these errors?

Thanks,
Claudio (Italy)