Error 0x011ddf27 on Avira Antivirus Personal

I’m having problems with Avira AntiVirus Personal. After using it for few months already, it just suddenly malfunctioned. The error occurred I think after setting up the automatic scheduled scan. I set a weekly scan for my computer. It worked well at first. Then it just stopped. The window disappeared before it finished scanning.
Then an error message popped up saying: "avscan.exe – Application Error. The instruction at 0x011ddf27 referenced memory at 0x00000000. The memory could not be read." I already have tried manual scan but it still did not work.
