Outlook 2007 problems

[aaqib]

I have an admin machine using outlook 2007. We use Zimbra for our emails and it is synced to outlook for this particular machine. It was working fine up until this morning where it started to repeat messages constantly downloading from server. I had this problem on a previous machine (XP SP3) i tried a reinstall of outlook but it didnt fix the problem. I then came to the conclusion that its the PST file so deleted it and started from scratch. Still having the same problem. I'm now thinking its a problematic email on the server (Zimbra). but i'll be guessing, any advice? MAchine is Windows 7 Office 2007.