Ashampoo FW has definitely caused conflicts in the past; once uninstalled by the vendor's uninstaller tool, all worked well with users and Avast. Asyn and I worked with several users who had this problem and all had the same results of things working fine after uninstalling this FW. It might be worth a try, then reboot the machine.
However the XP FW is only a 1-way very weak FW. So I suggest you have something ready as a back up for protection, even if it is a trial third-party 2-way FW such as Online Armor, Outpost, Comodo (without AV) - all of these come as free and paid versions and have not caused conflicts with Avast.
Initially after unistalling Ashampoo FW, turn on your XP FW , reboot your machine, then test to see if this resolves your problem.
If not, try an Avast Repair:
- Go to Control Panel > Add/Remove programs > Avast Antivirus.
- Scroll down and choose Repair function in the pop-up window.
- Reboot.
If this does not work, then an Avast uninstall (using the Avast Uninstall Utility Tool
http://www.avast.com/uninstall-utility and clean install would be required. Then install your other third-party FW after this.
Let us know if you have any questions. Thank you.