I've always had problems with Malwarebytes 2.0 on XP. It didn't matter whether I had Avast or Panda as my antivirus. I have no problems with the old Malwarebytes 1.75. That doesn't clash with anything. I'd go with the current Avast, MCShield, CryptoPrevent, and the old 1.75 Malarebytes...but, as ever, it's up to individuals to make their own choices.