Today, I got a new Exchange account to replace my existing one. After copying everything, I only had to get my Xda neo to sync with the new account. This did not prove to be that easy, as simply changing the configured account led to interesting errors. Not only would ActiveSync always give me an error, it also produced errors in my PIM's contact list. It would show all contacts for a split second, then only show about half of the contacts. I tried to remove them all, but was only able to remove those shown. The others remained and broke the synchronization process.

So, how do you solve this, you ask. I don't know, if this is the best way, but it was the only one I found and that solved my problems without having to hard-reset my device:

1. Rename the file 'pim' to anything else and restart your PIM. This will clear all contacts, calendar entries, tasks, etc. If you don't sync all these items, you should probably make a backup first!
2. Remove the mobile device from the ActiveSync connections
3. Create a new connection to the PIM and start syncing with the new settings

I realize, this is not very comfortable, but at least it works and leaves the rest of your device intact (i.e. installed programs, customized sounds, etc.).