Strange files appearing in forum folder

[Kalandor]

Hi all

After my forum being hacked last week (I solved this issue and updated the forum) I now have stragange files appearing in my forum folder named "core.xxxxxx" where xxxxx is some random number. Every file with size of 22MB quickly filling my space quota. Any suggestions ?

[Kindred]

core files are usually due to major server errors....   check with your host.