Since installing avast free version, i cannot browse my HTC Touch Cruise using Microsoft Mobile Device Center. The calendar and contacts synced OK but I couldn’t browse the files on the phone. Avast help suggested re-installing MMDC but now I can make no connection at all now. All I get is a unhelpful beep from the computer. The PDA thinks it’s connected, but the computer shows nothing.
Hello skydog and welcome to the forum.
I am posting a few links for you to review. One of them is a forum should you not be able to get an answer here, you can post it on a specific forum for these types of problems (and others have had these problems and they were not AV-related).
http://www.microsoft.com/windowsphone/en-us/howto/wp6/sync/installing-wmdc.aspx
http://social.answers.microsoft.com/forums/en-US/windowsmobileactivesync/threads/ - forum
Since I do not know your MMDC version or your machine OS, I posted the download links above, but you may have to do a search on your own since I did not know the above information from your post. I would suggest that you uninstall it again, reboot, and reinstall it. You should see that you device is now recognize by your machine.
Make sure your USB connections are secure and in the same USB port that you used previously.
Also, make sure you have not renamed your PDA device as this will cause difficulties with your syncing.
Hopefully you made a backup of your calendar and contacts prior to all this happening. If not, do you at least have a back up on your PDA itself?
Try the links above and the forum link and let me know if this help you. Thank you.
Hi Safesurf, and thanks for the reply. While I was searching for a solution, I un-installed avast, and hey presto, syncing was fine, so that suggests something. The initial strange behaviour was that the contacts and calendar items synced OK, but I couldn’t browse the phone memory or SD card. Uninstalling MMDC and re-installing the latest version lost me the ability to sync anything - MMDC simply showed “Error”, very useful - until I uninstalled avast, when everything started to work OK. No data was lost, except any entries I made while the sync was disabled.
So not sure about next move. If I’m feeling brave and have a spare half-day I may try avast again if I find out what is causing the conflict.
Thanks again for the helpful response.
If you would like, you can contact Avast Customer Service http://www.avast.com/contacts to make sure it is supported and report back. I don’t know see why it would not be supported, but it is worth confirming.
Therefore, I would back up your information, and on a day you feel “brave” reinstall Avast…reboot. Perhaps you just need a clean install. 
Let me know if you have any further questions. Thank you.