Hi John, I have been in touch with Parallels support regarding this issue throughout last week. After an hour long support session and finally replacing Microsoft Security Essentials (free from Microsoft) with Kaspersky (pushed by Parallels and costs â‚¬) I was left with the same issue! I get the impression that Parallels know full well that they have a problem and are just "threading water". Based on your reply it would appear that you may have been through other "cycles of despair" with this product, as you have been using it since V3. Is this the case? I am coming to the conclusion, having trawled through various forums and websites, that this product has always been unstable and that there is a fundamental issue with the underlying software architecture.