Eddy
2
- Disable system restore
- Reboot
- Run a full system scan
- Remove all infected files
If you still have Panda Antivirus installed, you must not remove those files ofcourse 
Here you can find what is known about Avast detecting infections in Panda files:
http://www.avast.com/eng/support/faq/avast_4_home_profe/virus_detection_and/false_alarm_viruses.html
In general it is not advised to have two different anti virus applications running at the same time.