I am having the exact same problem. I just hard reset mine. Still had the same issue. So I reinstalled the Saridnours’ AKU 3.5+ pr6, which installed without a problem. Then I tried to connect to Activesync again and get the connection problem. This is really puzzling.

Well I went through and tried to figure out what caused the issue by uninstalling the programs since it last worked. It appears to have been caused by the Cisco Systems VPN client v4.8.0.1.0300. I was able to sync for several hours, and then decided I would try to reinstall it to make sure it was it. Again it stopped working, so I uninstalled it again, but after the second uninstall it didn't work either, so it took a system restore to get it working again. Such an odd situation and I'm afraid it probably won't take much to break it again.

Are guys using BitDefender on you PC
 

I had similar problems and the problems was BitDefender one of their updates "broke" the synch. Search their support site for a temp fix while the come with another update.

Thanks

it appears that it is disturbingly easy to break activesync on our phones. hopefully htc will look at that in future aku's.

I guess I'll search the site for some sort of support. I'll let u guys know if I get some kind of results.

I also had a problem with AS. I had Alwaysbelieve's 3.5 installed btw. I got a laptop from work and would not connect for the life of me. I thought it had to do with the VPN software so I messed with my firewall connections, re-installed AS, different versions, etc etc. What was weird was that the phone would connect on the first time set-up only. When I disconnected the phone and placed it back on the cradle, it would not connect and stop working. I went ahead and installed the nice and clean 3.5 and re-installed AS again and it worked! I have not had any problems connecting or syncing since then.